The age of consent in the UK is 16. This means that its against the law for someone to have sex with someone under the age of 16. It wouldnt be illegal for someone whos 16 to have a relationship with someone who is 30 - unless that person is their teacher or in a position of authority.

Can you date a 17 year old in UK?

Yes. Legally, nothing sexual. It is an offence for anyone to have any sexual activity with a person under the age of 16. However, Home Office guidance is clear that there is no intention to prosecute anyone for sex with someone under the age of 16 where both agree and where they are of a similar age.