It's like putting a lobster pot in the sea, leave a question here for a couple of days then come back and reap the rewards. The internet is so cool.
Anyway, questions answered always throw up new questions but I will lean on common sense from here on in.
Probably run a fused supply from battery into relay then into small fuse board.
Halfords seemed pretty useless so will try Maplins (UK) and then mount/hide the whole ugly shebang inside left hand side panel as there seems to be plenty of space there and keep underseat clear for things I need regular access to.
Is there an alternative plug system for gloves, jackets etc. to the ridiculously outdated, oversized cigar lighter set up we all put up with?
I would even prefer to use bullet connectors in Vaseline, much smaller and less likely to shake themselves to pieces
have fun with your helmet!