Norfolk would be a good place, but I'm southern Germany at the moment... lol. A long flight for that. I can get to FL100 as it is all Class E to that level here, except for around the big airports where it is C/D. So I can probably get a good idea of climb performance to that level. I think it is C above that, so could probably ask Lagen Info for higher, they might say bog off... but you never know.
No problem, in 9 out of 10 cases you will get permission to enter airspace C in Germany as long as they get the impression that you know how to fly an airplane and do radio communication. Just give them a reason so they know that not granting the request would mean an inconvenience to you. Note that airspace E extends up to FL130 in the alpine area in Germany (marked on the VFR maps). Some months ago I went to FL200 just for fun and to test my oxygen saturation, no issue at all. They might give you a few vectors so you stay where they want you to be.