Thanks! I can do more than 1000 fpm, I would also want to do FL180 (unpressurized, but on oxygen - this is a Cirrus SR22 Turbo). So, if remaining in controlled airspace, I would get the clearance on the ground? Also, on approach, would ATC route me through controlled airspace or would they at some point "dump" me into Class G with some sort of service level that no one outside the UK has ever heard of?
BOAC, by way of explanation: In most of Europe, there is no "joining the airways". You are and remain in controlled airspace during IFR flight from take-off to landing, or at least under control of ATC. The (rather nice and very handy) concept of regularly flying IFR in class G without a clearance or even radio contact, let alone a flight plan, is rather foreign to the rest of Europe. As you can see, I really like the concept for its practicality and ease of use, but I have found one really needs to know how to "work the system" if one wants to cross from class G IFR flying to "airways" flying. For example, it took me several visits to the UK to learn that requesting an "IFR clearance" won't get you anywhere with ATC. The magic words are "airways clearance". Try that phrase anywhere else in Europe and I wish you good luck...