Okay, crazy question; can (relatively) old adults take A-levels? It might be fun to try to pass tests in things I've never taken formal coursework in like psych

Okay, crazy question; can (relatively) old adults take A-levels? It might be fun to try to pass tests in things I've never taken formal coursework in like psychology or European History. I did some snooping for US AP tests and at first blush it looks as though taking the tests is restricted to high school students, but perhaps one of the A-levels offering territories is less restrictive?