Copilot vs ChatGPT for UK Businesses: Which to Buy First

Short answer: if your business already runs on Microsoft 365 and the work lives in Outlook, Teams, Word and SharePoint, start with Microsoft 365 Copilot. If your team mainly writes, researches and analyses documents they paste in, or you don't use Microsoft 365, ChatGPT Business is usually the better first licence. Plenty of firms end up with both, for different people.

The rest of this guide is the detail behind that answer, written for a UK business of roughly 5 to 250 staff. It covers what each tool can see, how each treats your data under UK GDPR, and how to decide who gets which licence. We have left prices out because they change often. Check the current price on each vendor's site.

The one difference that matters most

Microsoft 365 Copilot works inside your own files. With the paid add-on, it answers from your email, calendar, Teams chats and SharePoint documents through Microsoft Graph, without anyone copying them in. Ask it to summarise last week's emails with a client and it can.

ChatGPT works on what you give it. You paste text, upload files or connect specific apps, and it works on those. It is a stronger general assistant for writing, analysis and reasoning across documents you bring to it, but it doesn't sit on top of your whole Microsoft tenant.

So the choice usually comes down to where the work already is.

Copilot and ChatGPT side by side

What Microsoft actually sells

Microsoft's naming has changed several times. As of November 2026 its own documentation describes three levels:

• Copilot Chat, included with eligible Microsoft 365 business licences. It is a secure chat assistant. It only works on organisational content a user uploads or has open, and it doesn't search your tenant on its own.
• Microsoft 365 Copilot, basic access, which puts Copilot inside the Office apps without the add-on.
• Microsoft 365 Copilot with the add-on licence, which grounds answers in your mail, files, meetings and chats automatically. This is the version people mean when they say "Copilot can read my inbox".

Most small firms already have Copilot Chat and don't know it. That makes it the cheapest place to start: switch it on, write a short policy, and see who uses it before buying add-on licences.

What OpenAI sells to businesses

For business use, the relevant plans are ChatGPT Business, ChatGPT Enterprise and the API. The free and Plus plans are consumer products. A business that lets staff use their personal ChatGPT accounts for work has no admin control over the data, and on consumer plans OpenAI may use conversations to improve its models unless the user turns that off.

OpenAI says it does not train on business data from Business, Enterprise or Edu by default. Enterprise adds the option to store data at rest in Europe, along with stronger admin and security controls. For a team of 10 to 50 people, Business is usually where a UK firm starts.

The Copilot risk nobody mentions: your permissions

Microsoft says Copilot only surfaces organisational data that a user already has permission to view. That sounds reassuring, and it is accurate. The problem is that most SharePoint and OneDrive estates have years of loose sharing: "anyone in the organisation" links, old project sites, an HR folder shared to the whole company years ago and never locked down.

Before Copilot, nobody found those files. With the add-on licence, a junior member of staff can ask a question and get an answer built from a salary spreadsheet they were never meant to see. Nothing was breached. The permissions were already wrong.

So the first job in a Copilot rollout is a permissions review. Training comes after. Microsoft provides tools for it, including SharePoint Advanced Management and Restricted Content Discovery. We would run that review before turning on the add-on for anyone outside a small pilot group.

UK GDPR: what you have to do with either tool

Neither tool is "GDPR compliant" or not on its own. Compliance depends on how your business uses it. With either one, a UK firm should:

1. Use a business plan, so a data processing agreement covers the service.
2. Record the tool in your records of processing, with what personal data goes into it.
3. Check where the data is processed, and the transfer safeguards if it leaves the UK.
4. Run a data protection impact assessment if staff will use it on customer or employee data at scale.
5. Give staff a written policy on what never goes into a prompt.

Our guide to whether ChatGPT is GDPR compliant goes through those steps in more detail, and the free UK AI policy template covers the staff rules.

How to decide who gets which licence

Buying a licence for everyone is a common mistake. Usage tends to be uneven: a few people use an AI assistant every day, and a larger group barely touch it.

A better approach is to look at what each role does all week:

• People who live in email and meetings, such as account managers and directors, get the most from the Copilot add-on.
• People who write, research or analyse long documents, such as bid writers and analysts, usually get more from ChatGPT.
• People whose work happens in a line-of-business system, such as a job system or a CRM, often get little from either. Their time is saved by automation built into that system.

In many businesses that group holds a large share of the hours, and neither licence reaches it. Our AI readiness audit counts where each person's week goes, so you can see which roles a licence would help and which need AI automation instead.

Questions UK businesses ask

Is Copilot better than ChatGPT for business?

For work inside Microsoft 365, yes, because it can answer from your own email, files and meetings. For general writing and analysis of documents you bring to it, many teams find ChatGPT stronger. The right answer depends on where each person's work happens.

Can we use the free version of ChatGPT at work?

You can, but you shouldn't for anything involving client or personal data. Consumer plans have no business data processing agreement and no admin controls, and conversations may be used for model training unless each user opts out.

Do we already have Copilot?

Probably, in its basic form. Copilot Chat is included with eligible Microsoft 365 business licences. The version that reads your mail and files needs the paid Microsoft 365 Copilot add-on.

Does Copilot or ChatGPT keep our data in the UK?

Neither offers UK-only processing for these products in the documentation we checked. Microsoft keeps EU customers' data within its EU Data Boundary, and says customers outside the EU may have queries processed in the US, the EU or other regions. OpenAI offers European data residency for Enterprise, Edu and the API.

Should we buy both?

Often, yes, for different people. Start with Copilot Chat for everyone, then add a small number of Copilot add-on and ChatGPT Business licences for the people whose work suits each one. Review usage after three months and move licences to the people who use them.