Doing physics, math and psychology a2 at the moment but with a different exam board. In terms of how difficult they were at as, found maths completey fine, psychology ok once I knew the structure of the essays well and physics fine once I'd done questions.
For physics I'd advise making sure you 100% understand everything taught before you leave the lesson as some of the concepts can be a bit a difficult to get your head around at first but once you understand them they're completely fine.
In psychology make sure not to leave note making until the end of the year as there is a lot of content to summarise, it's also nice to keep notes organised so you can find them all when you next need them. I had partially completed by notes by Easter so it was quite stressful to make all the ones I needed in time.
In terms of revision for physics and maths I didn't waste time on making notes and just did tonnes of past paper questions on every topic, it worked well for me.
Gl