On dep from FAB clear you to 3400' (TMA at 3500') and say 'remain clear of controlled airpace, contact London...'. That would throw a foreign pilot too. They are unlikely to know where the contolled airpace is. Surely the clearance to 3400' on it's own should be enough?
If a light aircraft pilot busted Controlled Airspace, then they would be lambasted. It should be the same for a professional pilot.
As a GA pilot, if I go and fly in France or the US or anywhere else for that matter, I do my homework and look at their rules and regulations, buy the appropriate charts, and try and keep my nose clean. For a professional pilot operating commercially in a foreign country, why should we expect anything less ? In someways it should actually be easier for them as many will have an Ops department who can supply them with all they need in terms of support and data filtering. Professional flight guide and chart suppliers also supply the relevant text in their documentation, all it requires is someone to make the effort to read it.
Failure to prepare is to prepare to fail ..... and that's just as relevant to professional pilots as it is to GA ones IMHO.
Of course, it would help immensely if the UK just stuck to ICAO procedures, instead of using a bastardised bespoke procedure for a bastardised bespoke airspace setup.