I have been a monthly client with MM Bubbles for more than a year now, and the service has been consistently of very high standard.
The prices are very affordable; make sure you inquire about the voucher option which would make your mani pedi session cost a mere £45.
Niko's service is also of very high standard, I am not sure you can get any better in London. I always make sure I can be seen by her when i visit the salon.
Overall, cannot recommend enough this place.
My hairdresser barely spoke english so it was difficult to really describe what I wanted (but I wanted something very basic so it was fine) and she did a good job!