It's:

b+ (over 90% I would say).

You can physically do the transfer in 40 minutes if you're sharp, 2 hours should be fine, though of course, due to the c word you need to be in T5 for 10 o clock.

I do this sort of connection a fair bit, it wouldn't bother me, but if you are easily fazed by travel then best go later. And yes you can do this airside, with or without a boarding pass (can be issued in Flight Connections T5).