I must say as a very regular user of LGW, who actually found it in many ways preferable to LHR, I shall now be very much restricting my flights from LGW (probably to a few JERs), if what has been posted in this thread so far is remotely true.
No Champagne at a BA home hub. Not just no vintage Champagne, no rosé Champagne, but no complimentary Champagne at all! If BA pax can be given chits in AA lounges for free alcoholic drinks, is it beyond the ingenuity of BA's Gatwick management to agree the same with No.1?
In the case of LGW premium flyers, many are leisure travellers who have paid their own dime and want the full BA premium experience. No Champagne for a GCH flying in F. Need I say more.
As for lounge capacity restrictions, BA's own only ever affected guests on very rare occasions, usually huge number of IRROPS.
In this case BA should have agreed that its own pax, by virtue of cabin or status, must always be admitted, but any restriction can be applied to guests.
The idea that someone flying an cheap LCC SH flight will be allowed in if they pay, but a BA F passenger will be turned away "due to capacity restrictions" is frankly ridiculous.
If I were BA, I'd just rip out all the J (and F) seats in your LGW 777s, as I doubt you'll be wanting to fly them empty come mid-2016.
LGW's owners have presumably done a deal with BA to cover the move to the South terminal and the interim arrangements. That ought to cover continuance lounge provision in more or less its existing form. A separate F lounge might be pushing it (but premium drinks and free food for F and GCHs would not), but limited capacity and no free Champagne is hardly anything like existing provision. It smacks of an inexperienced junior manager trying to be clever.
It would be interesting to know who is pocketing the saving on this one - LGW's owners or BA.