There is no FBO. Talk to the Air Base Command Post (ABCP) soonest. Assuming they give you permission they will tell you where your parking will be (most likely at Air Movements) and will tell you about access. It's not quite the same as a civil airfield as the security is at the perimeter rather than at the Tarmac edge.
Amberley is a big base and Air Movements is no where near most places. Agree with Keg you need to talk to the AAFC people you are meeting, if for no other reason than you will need a lift!
As far as the flying procedures go it s just like any controlled airport if it is active or like any CTAF if it is not. On the weekend you probably won't see much in the way of fast jet traffic. Most likely single transport moves if anything at all.
As gutso said, they don't bite.