pa:
Are you running on an ordinary 'road' course, or on some kind of oval? I find it very hard to believe their 'technical' excuse, but if your circuit has conventional curbing, that is usually the biggest obstacle to using a track in both directions. Also, the runoff areas are generally designed for people taking bends in one direction only. I would imagine that an oval track could avoid both these problems.
(I suspect that car circuits have all the marshalls' posts designed to cope with impacts by cars running just the one way, but I've yet to see a kart track where this was the case.)
I suggest you post this query to
www.karting.co.uk on the Noticeboard; the UK uses loads of engines like yours, and there's usually quite knowledgable people posting/replying there.(Just don't take any of the 'banter' too seriously....)
Everyone Else:
Can nobody confirm the direction of the other UK circuits?!?