I add that no university requires applicants for places to study law to have obtained work experience before university. If your school suggests otherwise, your school is mistaken.
Please note also that you don't have to study law at university in order to qualify as a lawyer. About half of those who become lawyers have law degrees, and the other half don't. The utility of A level law is debatable. I think that it's a waste of time, but others disagree. It's not necessary, and some say not even useful, for those who go on to study law at university. A parallel might be the Noddy physics which people learn when young, and then have to unlearn when they go on to real Physics later (for example: aerodynamics - lift doesn't suck).
What attracts you to working in the legal profession?