They are not of the same level and there is nobody as I understand it the *specialises* is FFS. Sure, you can get rhinoplasty, or whatever, but they are not specialists in feminisation. That is important. Its also more expensive than Bart plus a plane ticket. Its really a no brainer.
As an aside, he is a nice guy. Not that its relevant for surgery, but he makes trips to foreign countries repairing cleft palate for free for children in poverty stricken regions.
Bart charges different amounts for different procedures. To know for sure you would have to contact them. They would require that you have a consult with him in canary warf london first though.