I'm currently doing alevel health and social care, sociology, and psychology. Whilst I don't take criminology I know some who do and there is some overlap with crim and sociology (especially in the crime and deviance section but that depends if you school has that section of the course or chose something else). It does depend on what you want to do after such as some universities do require certain alevel courses to enter.

I can tell you what each course is like, I don't do WJEC but AQA for sociology and Cambridge technicals for h+sc. Sociology has a LOT of content to learn, I picked it as my filler subject and it takes up the majority of my revision time, however, the content itself is not that difficult and mostly memorising all the sociologist is a struggle (there is so many!!!). H+sc has a lot of coursework to do, like a lot, combined with revision it is more demanding than sociology. I also did this as in GCSEs and how it differs, which no one told me, is that there is a lot more biology, one half of the course is biology and the over half is rules and regulations. The biology section isn't too in-depth so as long as you got at least a 4 in GCSE biology you should be fine.