If you roll your France battle first and do your retreat before you do the sea battles, UK will know there is no sealion threat and they should scramble, especially if you bought all ground units. If they don’t scramble and opt to stack france instead, you’ll kill them G2 along with the French. This costs you time against Russia but if for some reason you really really want UK to have no planes this could be a way to ensure it. I don’t think you’d fare very well on the Eastern front from that point on though.
I’m fairly sure all scrambles are declared before any combat is rolled, but I could be wrong.
That said, I agree with Uncrustable; Germany can help Italy get on its legs in other ways while buffing itself up too.