Definitely try a beginners course at an AGA shop. You'll be amazed at how much food can be produced at one time!
Buy the AGA roasting tins and line them with Bake-o-glide. They fit directly on the runners in the ovens then you can fit more in. It certainly helps if your saucepans have metal handles so they can go directly into the ovens too.
Use the cook everything in the ovens method as much as possible. This saves fuel. So start things off on the hot plates then transfer to the appropriate oven and just let it cook away in there. A cast iron casserole dish is very handy.
Use oven gloves. I have always hated oven gloves but had to get used to them once we had an AGA. I use the long 'gauntlet' type ones as its really easy to burn your forearms when fishing pans out from the back of an oven (they're really deep).
A friend lent me a book book called 'The Complete Book of AGA Know-how' by Richard Maggs which has been absolutely brilliant and I still refer to it when a bit unsure about the best method to use (must give it back to friend! Oops!). Highly recommended.
We love the toast rack, it really does make the best toast. Pre-warm it on the boiling plate for 1 minute before putting the bread in it, then it won't stick.
We have two stackable racks which sit over the closed lids and are fabulous for drying everything. Load them up with laundry in the evening (when you're presumably not cooking anything) and everything will be dry in the morning.
The circular chef pads which sit on the lids are also v handy and protect the domes from getting scratched.
A good razor blade type scraper is also essential for scraping the gak off the top. Trying to use a cloth and get a good result while it is switched on is hopeless. Also, NEVER use the 'power spray' type cleaners on the enamel. It will wreck the finish and there will be no going back.
Can't wait for ours to go back on either! Looking forward to roast dinners, pancakes made on the simmering plate and airing the laundry from the washing line!