Hello mate,
Good luck with it all, I'm in a similar situation to you (I also live in London and flying to the US in 7 weeks time).
Ron Shapiro is in the top 3 or 4 surgeons so you have nothing to worry about. You have chosen extremely well.
I'm taking 5 weeks off work and hoping it will be less noticeable after that period. A lot depends on the redness but in the final week I'll be experimenting heavily with concealers etc.
Yes, I'm thinking of going to a different hairdresser. Mine is very close to where I live. I'll probably only require a buzz cut anyway. How about searching for one that does home visits?
Large Tesco stores sell a lot of cheap hats/baseball caps. I went and tried lots on to see which had a loose fit. How about a Panama?
I dye my hair and have not asked yet how long I should wait. Hopefully I can do it before returning to work. I'm not that grey so it's less of a problem.