Sizing-wise, my feet have similar size as yours, maybe a bit bigger. I am UK 7 in almost all brands I tried, eg C&J 348, Merrmin, Carmina Robert Last. I initially ordered size 41.5 in F last based on Mr. Kuti's advice, which some people said is often on the big side. But then, I have a kind friend offered me a 40 (also in F last) and it mostly fit or just slightly too long (but not long enough to have heel slipping). So, I have amended my order to 39.5G , which according to Mr. Kuti has slightly shorter length than 40 but roughly the same width.
Depend on the desire fit of you and how aggressive you are in finding the best fit size for the first purchase, I think 40.5 will be big for you but u can always add an insole. If i were you, i would at least go down to 40 or even 39.5. I will not be surprised if you finally land on 39. Take everything in my post as a grant of salt though. I have limited experience as you can see. Sorry if I have confused you further.
I have no experience in proxy. So, no info.