At GCSE we had blocks but they weren't really that restrictive. We had to do Maths, English Language, English Lit, D&T Graphics (ugh) at least single Science and ICT (we originally had the choice between GNVQ intermediate and advanced but in the second year they decided to make us all do Double Applied GCSE instead which was part of the reason why I got a D lol)
At A Level though, it was completly different. We had blocks and each block only had like 4 subjects in it. There was the option to take subjects at these two other schools that we were in a consortium with but I couldn't be bothered tbh. Instead I went to a sixth form college where there were still blocks but most subjects were in at least 3 out of 7 blocks so virtually nobody was disadvantaged because of it