cjboy, you can get all the airways clearances you like on the ground, but the chances of being cleared to climb to even FL250 is unlikely whilst under control of particularly the French.
I flew the c550/ 560 five years ago. the 560 was fine cruising at .73 but exchanges with A.T.C. in the 550 almost always went like this:
" G-AB requesting climb "
" G-AB what will your speed be at ( say ) FL250 ? "
" ERR. .62 "
" Roger G-AB, maintain FL200 for the cruise " !!
There of plenty of places in Europe where you will get to Fl300, no problem but in busy airspace you simply can't get in the way of other aircraft flying much faster.