I only tried my shoes on briefly last night. When I get home, I will try to confirm fit, but I have a feeling I will return and get 40.5. The tiny bit of heel slip worries me. Back earlier in this thread (Sep 2013) Torsion had the exact same issue as me and ended up taking 1/2 size down. In April 2014 of this thread rikod made a post saying with 90% confidence that unless you have wide or fat feet, you should take 40.5 in F last if you normally wear 7UK. And since most people wear the same F and U last size, I would take a 40.5 using his scale.
Also, I've never tried a tongue pad or insole on shoes before so that could be a possibility but I'd rather have a shoe that just fits as is without these modifications.
Agreed - I did have the same issue, the hardest thing is the ability to size correctly with a new brand especially online if you have not physically tried on the shoe IMO. Following the advise of others on here when I posted photos of the initial pair I received, I returned and I sized down and the fit is now perfect. For the money spent I didn't want to go with the option of heel or tongue pad having already previously owned some mis-fitting shoes and NEVER going down that route again.
You won't be disappointed once you get the right ones!