Here's a tip............ try doing at F240, file the appropriate SID from AMS to route via NEPTU, and you'll be amazed how hassle free your life will become.
Midland do it every day EMA - AMS - EMA.
Once you cross NEPTU, you are technically in the FIR , and you work London Mill', but before you give me the bull**** about not flying outside controlled airspace, why shouldn't you?
You get a radar advisory service, and whilst the airspace is very busy with the military, providing you don't plan descent until about 20nm west of Norwich, you'll be OK.
In the event of London Mill not being able to work you, Norwich can provide the same radar service for you at no extra cost, as they occassionally do to BD.