Brian, many thanks for the constructive input, I'll look at loosening the fit of the tongues. Would a loose fit be OK, I was concerned about keeping the fuselage sides straight with out having to use a straight edge to align it.
The fit of the wingtube is designed to be tight, this is now proving to be a good thing as the two piece wing is about to be flight tested. It passed the static load test with no problem.
Regards
Bob