Relacs.com - Andy Berkowski's website has some great articles in the BLOG section.
This article compares Buprenorphine to methadone
For those with refractory RLS, which doesn't respond after augmentation on dopamine agonists, these 2 drugs are often the only ones that help.
This article may help persuade your UK neurologist that these drugs are effective.
It appears that Buprenorphine is actually better than methadone.