A-levels are the standard UK qualification for entrance to university.
You shouldl take them unless there's a very good reason why you can't.
Access/foundation courses are designed as "short cut" university entry
for older people. They vary a lot in quality, some are properly
approved, others are just put together by private institutions who are
trying to make money from those who don't know any better by offering
poor quality education which won't get you a place at any decent
university.
Many of the better or more prestigious universities wouldn't offer
places to those who have only access/foundation qualifications -
particularly someone of your age. The question asked would be "why
didn't you do A-levels?".
Matthew Huntbach