Just wanted to weigh in on the realities of working in law. I'm an old person who works in private practice and has worked in law firms since before you were born probably (and that pains me to say).
It depends what area you work in but you mention wanting a 'good' job, so let's assume you work in the City.
You say you're not a good public speaker and you're quite shy or socially anxious. Lots of lawyers are not good public speakers or are quite shy. Quite often, especially if you're in a huge City firm and doubly so when you're junior, you won't be speaking that much to clients, so don't worry about that. Day to day, you don't really need to do public speaking. Plenty of lawyers have bad people skills (I'm not saying you do!) - generally the smarter you are, the worse you seem to be at conducting yourself like a normal human being. It's fine. Everyone has their place. When you get to the stage of forming your own following of clients, there are different personality-types of lawyer for different personality-types of client. All I would say is don't do yourself down.
In the beginning, you'll have to get chummy with your cohort of trainees and you'll have to get to know the department you're put in. That's all you need to focus on socially. Then you may start sending emails to lawyers on the other side etc. It depends if you're doing transactional or litigation work. You'll be exposed to clients gradually and you'll learn to network gradually. I used to HATE it but now I go to events and know at least 60% of the people there. I've spoken at loads of events and things and the first time I genuinely wanted to get knocked down by a bus on the journey in but, again, just know your stuff and take some rescue remedy. Don't worry about it at this stage. You'll be fine. Just remember: all clients, opponents, people you work for etc are just people at the end of the day. They might be fire-breathing, scary-as-heck people sometimes but more often than not, they're reasonable and practical.
Next, debate situations. Again, it depends what area you go into but in reality you're very unlikely to have to do 'on the spot' debating. If you're doing dispute resolution, depending on the size of the disputed amount, you may have to have some more intense phone calls if back and forth by letter or email doesn't work but you'll still know all the facts of your matter and what your client wants etc. Bigger claims (as in..."better" jobs) will have loads of back and forth via email etc and robust letters, again, you'll know the frame work of your argument and it will move at a glacial pace. Plus, you'll have a barrister who is kick-ass. They are genuinely freaking amazing. If you're planning on being one of them, good luck. I honestly don't know how they are so whip smart, put together etc.
I'm leaving out things like family and criminal etc because....*shudders*
Finally...research. You won't have to do this forever. You'll have to do it as a trainee but honestly after that...it'll be rare that you'll have to research. You end up in the position where you know your area of law very well and you're just applying it to the facts that come in. Things that require ACTUAL law-that-you-have-to-look-up law for me, at least, in a commercial-ish transactional-ish role are not so much. Anyway...I'd just ask a trainee to do it. 😉
All this to say: you are being too hard on yourself. Don't do yourself down. You got this!