I see nobody has answered you! I had my first child with NHS fertility treatment at Hammersmith, so always recommend them. I am currently expecting number two, using fertility treatment from Bourn Hall in Cambridgeshire. Depending on where you live, I would say the treatment at Bourn Hall was less stressful (although that could have been because we knew what was happening) and the drive there was certainly nicer than the drive to Hammersmith. Hammersmith always felt like a conveyor belt, but on the upside, I could leave home at 5am, get there when it opened at 7am, have my scan or whatever and be back for work at 9.30. Bourn Hall use an appointment system for scans etc so I had to use leave to go there.
I would not recommend Herts and Essex, who we used for 2 frozen embryo cycles, and felt they messed both of them up.
Obviously this is just my personal experience.
Good luck with your treatment. Xx