Also just to point out, you might meet your offer of two Bs for Liverpool but if you are planning to become a solicitor or would like to keep your chances with top firms open, most of them stipulate a certain amount of A levels/UCAS points. I don't know how many points a BTEC is but you should definitely check.
And I agree with the above, when you study boring horrible subjects like land law, contract law and EU law you can't just give up. You have to study them as part of the law degree, so I think it would be worthwhile for you to learn to make yourself work even when you don't enjoy the subject. It will be a useful skill for studying law.