Went backwards and forwards between 11" and 13" and decided to go for 11" as I currently use an 11" iPad and that seams to work fine for my usage. I didn't bother with the Magic Keyboard as it isn't a replacement for my MacBook - I use my current ipad for drawing, note taking and general simple computing (m4 definitely overkill for email!). Ordered the new pencil pro too which sounds a great upgrade to my current apple pencil. All in all it should be a nice upgrade to my 2018 iPad Pro.
Separately I've ordered the rebound magnetic case from ESR along with Armorite screen protectors as my 11" iPad is the only apple product I've ever broken the screen on though the Armorite screen protector did it's job on my iPhone when I fell over (walking across a pitch black car park and fell over a raised curb that I didn't see - iPhone went about 30 feet face down but only the screen protector and case were scratched). With the 15% discount you get for signing up to them the total came to £35.78, so just over the £33 minimum for free postage.