DS1 went to Graz in 2010 not for tube-weaning but because his feeding behaviour wasn't normal and his growth was at the point where a tube was being considered. We were anxious to avoid this at all costs. This was because of sensory processing disorder which his consultant here wished to have classified as autistic spectrum and had thereupon washed her hands of. We can't get a paediatric OT with expertise in sensory issues here at all.
They provided three weeks of pretty intensive paediatric sensory OT and that and the Spielessen (play picnics) got him to eat reasonably, although he is still pretty picky he began to feed himself, ask for food when he wanted it, and take a better diet (he nevertheless needs one high in calorific content).
In addition he saw their Dr Gudrun Schein, psychologist, and has been back to see her in 2011, to advise on the most suitable educational environment. We couldn't get an ed psych assessment here that was anything like as thorough.
Until we went there I had to keep saying "this isn't you usual tube-weaning case" and there was a tendency to pigeon-hole, but when they got him in there they had the measure of him at once and he was stealing Wiener Schnitzel off my plate in the Hauptplatz within a week. He wouldn't have touched it beforehand.
Apply to your health board for funding and cite Article 56 of the EU Treaty, that gives you the right to look for treatment abroad that isn't available in the UK. They are sort of exporting the technique now though and I think you can go and see Prof Dünitz-Scheer in London for a preliminary consult and Spielessen. Then you could go to Austria for the full works and you can also do it by online coaching.
There's now a company which arranges all the "health tourist" package of travel, accommodation etc without hassle but I think it's pricier than booking your own stuff, which is what we did.
When we were there they had about a dozen kids with tubes of various kinds and IIRC only one of them didn't get off it and that was because she was ill with something unrelated.
PM me if you need more info :-)