Hi Neil, welcome to the site. Good thing about these old bikes is how simple they are to work on. For basic maintenance up to intermediate tasks you don't need any advanced tools, but it's good to have a variety of screwdrivers, picks, ratchets and sockets, maybe a set of jackstands and a jack. Definitely pickup an impact driver (the one you hit with a hammer).
I have a 550F myself, don't you just love the header?