should i do a level history?

I think if you really enjoy History and are willing to put the effort in you could be okay, but the subject is very content heavy and requires a lot of work outside of the classroom. From my experience getting used to writing the essays in a short amount of time has been a real learning curve, and some of the content hasn't been the most exciting. Coursework is also an area that people either love or hate - it's more similar to how university works but the independence and workload doesn't work for everyone.
If you feel you would better excel in Criminology then go for it, just make sure no matter what subjects you pick that you're fully aware of things like topics, exam styles, etc.
History isn't super necessary to do law at university - it's favoured mainly because of the skills it teaches but they are ones you can pick up from other humanities like Politics and Sociology (which are a great combo btw!).

Have you looked at which topics/units your school teaches within the History syllabus?
Do these interest you - even if they are new areas?
Just be aware that Crim isn't an A level - its daft Welsh exam board Diploma and mostly focuses on True Crime nonsense with very little social theory. Some top Unis will not accept it for this reason. A level Sociology already covers deviancy/criminality - you dont need to do 'Criminology' as well.