I think Galloway is not far right, just an authoritarian opportunist. He can and will say just about anything for a few votes / party donations. He's morphed into a Unionist bigot in the Scottish context, why, who knows. He does seem to enjoy lost causes which were much more popular fifty years ago (Stalinism, British Unionism, etc etc).
In respect of "mainstream", I meant that the ideas are becoming common currency amongst a section of the electorate in a way unimaginable twenty years ago. Twenty years ago, if you were standing for a far right party, you could expect some physical confrontation and a lot of verbal abuse. I remember the odd BNP or NF leafletter running like a rat down the street after being confronted by a resident. Now we have a UKIP government who rubs their corruption and callousness in our faces, and gets away with it.
If this were twenty years ago you might get a UKIP candidate and maybe-maybe- a BNP or NF candidate, although far from guaranteed. Now there's 55-60% of the candidates from the far right. It doesn't matter that they will get only a handful of votes between them- it matters that they dominate local media with their poison and lies, in a seat where the last but one MP was murdered by one of their number.