I’m planning a gap year. Will this affect my chances of admission?

Absolutely not. We welcome applications for deferred entry and treat candidates planning a gap year exactly like other applicants. 

If you're planning a gap year, it's a good idea to have a plan about what you're going to do with your time, especially if you can demonstrate that this'll enhance your understanding of your subject.

If you're applying for a Maths-related subject, you should make arrangements to keep your Maths skills honed.

Unless the circumstances are exceptional, we tend to look less favourably on situations where we make an offer to an applicant who afterwards asks to enter in a different year from the year we've offered (typically the entry year stated in their application). We normally decline such requests because they usually mean that places which could have been offered to other applicants cannot retrospectively be filled.