How late can you defer?

Evening. I achieved ABB at A levels and an A in an EPQ - but applied for a course with AAA entry requirements lowered to AAB as part of doing an EPQ. I was still accepted into my firm uni, but I would like to defer for a year.
Would I still be able to defer despite being offered a place with a grade below the entry requirements? Is it too late 3 days after to defer?
Many thanks