Farage was never officially part of any the UK power structure, except the media.
He's an MEP. You can argue about their powers out his effectiveness, but he's an elected representative which I'd have thought puts him within the UK power structure.
The powers that the Members of the European Parliament have are mostly eclipsed by the European Commission, national parliaments (and for some stuff, the ECB).
Exactly. By his own measure, a waste of space.
That makes him part of the EU power structure, not the UK power structure.