Have you tried to get a GT3 allocation yet? If not, I'd work on getting a date with that movie star first.
Like all the others have said: P-car = best driving experience, M3 = more practical. 911s all seem to drive great. M3's are different with different generations.
I had an E46 M3, E92 M3 then I went with a 2013 335i. I finally traded that in for a 2017 F80 M3. I will tell you this: although the F30 and F80 look very similar (especially interior) they don't drive at all alike. I do not think an M340 is going to give you the same experience as a G80 M3. Also, there are loads of difference between even E92 and F80 M3s. So, even though I wouldn't expect it to be much different than and F80 M3, you really need to wait until you can test drive the new one to find out for sure how it drives. Wish I could be more help.
Cheers.