Thanks gents
Anyway been working on my new tool Airfix F4-F. Very nice and as is now typical with Airfix it's an excellent fit, indeed one coat of paint can spoil the fit. I had to clean the paint of the wing spars as they wouldn't go through the slots with it. Sand it off and

However..........
Read the instructions properly !!!!

If building with wheels down then jump from stage 6 to stage 12. The cockpit and undercarriage build up as one module not separate ones. I didn't notice and if I'd glued it in place I'd have been in a pickle, not impossible but fun

Anyway the fit of the cockpit is so good with the spars that I hadn't glued it so I could retrieve the situation. The undercarriage is very fiddly but is almost certainly accurate (I'd love to meet the Grumman engineer responsible, that's for sure). It does require very accurate clean up of the parts. The slightest burr left will affect fit. Providing you clean up properly it goes together very well however. Just take your time and follow the instructions.
The cockpit it'self is very nice and considering you won't see much of it is fine out of the box with some tape belts and carefull painting. Another winner from Airfix but read the instructions.