Games Workshop has from time to time sold official "generals accessories packs" that contain tokens for Middle Earth (eg. prone, and magic tokens) and pads of paper pre-printed for writing your army lists on:
https://www.warhammer-community.com/201 ... cessories/I'm not sure they currently have any of these on stock/available to buy.
I'm sure there are quite a few army builder or list-writing sites made by the community online ... although I'm not sure which are the best ones.
Most people just type up their own lists at tournaments and print them out, no need to have the official sheets apart from they're a nice colour. There are some examples of lists at the back of the rules book that show a good way to structure a list ... showing which warband is which, what the break point and total number of bows are etc. These are good to note on a list if it's one you're sharing with an opponent at the start of a match.