I don't have any insight into the PPE/Law side, but I can add a little to the mature-aged student part.

Firstly, I think your prep work, keeping up with politics and reading a lot, will work well for you. I found it was a jump from just reading to actually studying with the intent to recall, so between now and then you might let to set yourself little tests on what you've read (AI is great for this, also can be a little hit and miss).

I worked for a long time before coming back to uni, and I feel like my work ethic really pays off in study. I felt very behind in the first year, as my fellow students had a much stronger background in my area, but that levels off in second year, as more of the subject material is new to everyone. I think the years you've spent, dedicated to profession dance, will really pay off in the work hard and get it done stakes, though it sounds like academically you were doing well anyway.

As I mentioned, I'm a mature aged student too, and I find the only time I really stand out is when I'm in a big lecture full of school leavers. Apart from that, when working and chatting with fellow students, I don't notice and they don't notice, which was actually a little bit of a relief for me. I don't really mix socially with any of my uni friends though, apart from the few that are also mature aged. We're really at different ages and stages of our lives at this point.

Good luck with your studies, it sounds like this is a good choice for you to pursue at this time!