Hi,
As you've said Barton is a very busy airfield in terms of aircraft movements, also it has a large number of student pilots who may fly slightly larger circuits then the more experienced pilot.
The microlight circuit is the same as the fixed wing, 800ft AGL, you will find that a lot of microlights will fly a fairly close in base leg to short final however.
Rotary traffic is at 500ft AGL inside the fixed wing cct and will operate to remain clear of the active (except when crossing with clearance from the FISO).
The FISO should advise you of the fixed wing traffic ahead in the cct as you get downwind,(as you got on the microlight), it's then up to you to fit in accordingly - rather than flying further downwind how about an orbit, (if there was no one else behind), or alternatively climbing back to the overhead and repositioning so you have a bigger gap ahead - advising your intentions on the R/T?
What I have seen a lot of is traffic, say a P28R, following a, say C150. downwind, then base, then final, closing the gap all the time - they then have to go around and seem suprised that the slower aircraft is still on the runway when they get there.
Another issue can be an aircraft on base who thinks they can get in ahead of the aircarft on longer final, who then has to go around because the gap has reduced......
As you say not just EGCB issues, I'm sure most GA airfields have similar issues..