Tigger Too, I had exactly the same problem, filed IFR out of Lille into Fairoaks with a change to VFR over BIG so I could get a service from London for a descent to 2400 over BIG then VFR into Fairoaks.
Handed over to London mid channel, told to either route dct GWC or descend to remain clear. Annoying after a 50 min slot delay on a deserted apron at Lille. I chose to descend and continue VFR but very poor show from London, I might as well gone VFR all the way back and got home 50 mins earlier.