Going there this September for law and can only reiterate what others have said: grades, ps, and LNAT are likely the main things you need to focus on to get a spot. I had A*A*A* predicted, a 24 on the LNAT (which is a mark below what Bristol offers were averaging for this year), with a list of these supercurriciulars that I put in my personal statement:
Law in Action (podcast)
Understanding Contract Law (book)
Tomorrow's Lawyers (book)
America's Supreme Court (book)
CMS Connect (work experience)
Young Citizen's Bar Mock Trial (more extra-curricular but I put it in anyway)
Roe v Wade analysis
Chilcott report analysis
Granted, this is a LOT and probably way more than you need, so don't stress about amounts. For an effective personal statement you need to show what you've gained from either your subjects or supercurriculars (ideally both), so if you can show how a single book managed to open your eyes to multiple different things about the law, then thats likely to be better than 20 books that tell you the same thing.
For some book recommendations I would either suggest looking at Bristol's recommended reading list, which gives you a more 'catered application' (and is why I read the contract law book as Oxford had it on their reading list, bad move it was a VERY heavy read), or to check out these from personal experience:
Tomorrow's Lawyers by Richard Susskind (more modern take on the legal sector, easy yet interesting read, especially good for corporate law)
The Secret Barrister (better for criminal law here but still a good read)
America's Supreme Court: Making Democracy Work by Justice Stephen Breyer (a VERY good read, not necessarily UK-related but since its not read much, it can be a good PS piece)
The Rule of Law by Tom Bingham (whistle-stop tour of the legal world, personally found it a bit of a dull read but MANY law applicants have read it)
Law in Action (not a book but podcast, very approachable and has episodes on whatever you fancy really)
Work experience is not necessary by any means but I would recommend trying to do some work experience, whether virtual or otherwise, as it can be nice to put in your personal statement, or just to do for your own fulfilment. Again, no university expects it and does not give it any weight whatsoever. For this, Forage is a fantastic tool, you get very engaging and challenging virtual work experience from top firms, that is much better than the typical work experience webinar that doesn't provide much in the way of actual value.
All in all, good grades, a decent set of supercurriculars and a good LNAT score are likely the keys to getting a Bristol spot. Best of luck!
P.S. just saw LNAT-related stuff, if you're going to practice the LNAT I suggest finding some mock-tests online to get your head around the style of question they are asking, the test's format etc, and then using the official LNAT mock-tests to practice. The test is killer, so ensure you are learning critical thinking and analysis skills, reading academic articles as much as possible, and practicing it as much as you can. Treat it like another A-level!