I've never had a top coat react badly with decals, but then I've screwed up enough decals with over doing the setting and softening solutions!
I think the key is the second coat of Future over the decals as a barrier.
Couple of pics of the Hurricane...
I've drilled out the exhaust recesses ready to accept a pair of Hase ones from the spares box, much better looking than the airfix ones which look like blobs!
The silver on the leading edges of the wing are for the landing lights. Airfix just provide a blank box with a clear cover, so I've added a couple of punched discs to replicate the reflectors.
You can't see it in either of the above shots, but I've also hollowed out the front of the carburettor intake below the wing.
I should finally get to attach the canopy tomorrow, then it's off to the paint shop.
Karl