Just had a thought..
You can always do a law conversion course, as you don't need a law degree to be a lawyer/solicitor. You can do the conversion course(s) after your first degree.
I have friends who have done this and Law firms actively recruit non-law graduates. Ideally though you would want to study a good subject for a degree, if you really want to be a lawyer. English, History, Science etc. where you have to show reasoning,criticism etc.
Do a degree you enjoy though and work your hardest to get a first or a 2:1. A first will open doors to scholarships and stuff for your conversion course (not essential, but nice to have).
Also remember that there is no correlation between your A-level grades and degree result. Logically, there can't be. Most people in each class will have very similar grades, yet degrees are still awarded based on most people get a 2:1 or 2:2 and a few get a first, a few get a 3rd, according to a distribution. So as long as you go to a recognised uni and do a useful subject (I mean useful for you becoming a lawyer, the goal at the end of all this), then you can get a good degree, so your conversion and have a career in law.
It will still be hard as it's so popular, but there is hope if you want to work for it.