Making good notes is pretty much key to success in a levels. Yeah, sure you can just use textbooks but a lot of the things there are overcomplicated so it's best to narrow it down. I don't know how your sixth form/college/whatever has lessons but in my sixth form the teachers usually explain to us what we need to know (although depends on lesson) and then make us read the textbooks and make our own notes. It really helps as you process the information better and remember it as you have made it your own in a way. Although I didn't do the subjects you did, I think that perhaps my method can be useful for you anyway. I always rewrote my notes from class neatly and occasionally added more detail (if needed, wouldn't want to over-complicate it). Worked pretty well for me but then again I don't know what will work for you best