I think that if this a "VFR only" route, "Mode C required, sqwarking 7001" then it would be adheared to. ....or it should be, blatantly breaking the rules should have serious repocussions.
Besides, it could even be broadcast on an ATIS somewhere, "Heathrow VFR route open" or "Heathrow VFR route not available".
As for routing, directly N or South at 2500 should work?
