18 w/ 28 year old man

Guys I just have a question, my friend lives in the UK with me and she is 18. She found a guy who was working in finance but now is a teacher, he is 27/28. I am worried about her but they seem to be both really mature and understandable. As me and her dont know the law that much, do you think there will be any trouble if the girl’s parents consent with his age and position of trust?

Let me know please, I want to keep her away from trouble prior :)