I will try to help once again, please take note:
UK7 = US8 = 40.5 in the F
UK7.5 = US8.5 = 41 in the F
UK8 = US9 = 41.5 in the F and so forth
If GG, replace UK size for half size bigger, I can almost guarantee that is 90% accurate. Maybe the other 10% have wide or fat feet. For the U last if you have narrow feet (like me), same size as F, but must people upsize by half a size.
Just don't pay attention to what Vass says, they don't know, they have no idea.