Thanks everyone for the responses, they helped a lot. I think I have enough here to have a look at it next weekend.
I've ordered the replacement fuel pump/filter and hoses kit from beemer boneyard.
Probably overkill, but if I am going to have the tank off (again), I figured I might as well clean it all out again and replace everything - after 10 years, it could probably do with it.
Any recommendations on how best to go about cleaning the tank? Last time I just tried my best to rinse it out with clean fuel. Probably should get the missaz to do it, she is much better at this cleaning shit than I