I couldn't get NHS funding, but it's well worth giving it a go - even if the answer is no, you've not lost anything.
I know there is a significant cost difference having a band fitted abroad. I would be a bit concerned about whether I could see someone in an emergency - just before Christmas I had an episode of over-restriction. When I couldn't keep clear liquids down I phoned my provider and was having a de-fill within a couple of hours. It's worth asking about what would happen in an emergency, whether they have any arrangements with UK providers for emergency aftercare. The aftercare is really vital!