It’s not necessary to register for VAT unless your business hits the VAT turnover threshold. At the time of writing, that’s £85,000.
A couple of things to note:
- The threshold is based on turnover not profit
- You don’t need to be a limited company: sole traders can register, too
- You shouldn’t charge VAT on services unless you’re VAT-registered
You can choose to register voluntarily if your turnover is below this limit. There are situations where this may be useful, but it’s certainly a topic to cover with your accountant.
There are more details about registration on the GOV.UK website.