Gatwick or heathrow would be fine.
If Gatwick take the Gatwick Express train into London Victoria 30 mins (then tube) Victoria line one stop, change to Jubilee two stops.
If Heathrow use Heathrow Express (15 mins to paddington) then three stops on Bakerloo Tube. Aim for Baker Street/Regents Park tube station, and it's less than 5 mins walk to Harley Street.
I believe Dr Benito only does consultations on a Friday, twice a month or so. Consultation doesn't take long (15 mins) as lets face it there's only so much you can talk about a small area, though depends on what you ask i suppose. He's very blunt and to the point, will cop a feel, have a prod. No fluffy stuff, so something to bear in mind. Surgeries are done on a Wednesday in Barcelona.
Best thing to do is either e-mail/phone Aida in Spain (She's Lovely and speaks fluent English). She will give you all the info you need, will respond to e-mails very quickly, and will fill in all the gaps.
coordinator@cosmeticsurgeryabroad.org
Aida Masdeu (+34)606953331
Dr Benito´s Patient Coordinator
DEXEUS CLINIC BARCELONA
C/ Sabino de Arana,5-19
Edif. consultas 3ª Planta
08028 Barcelona ( Spain)
You can have the gyne & loves handles done at the same time. I wouldn't worry waiting until January, as you need 6 months to recover, leaving until then will delay you 'coming' out until late summer.