Ed,
Thanks for the response.
Ordered the rack and pinion from Rally Design today. They're a good price at under £100 delivered. Thought getting the rack apart was going to require special tools but mine was absolutely straight forward as pinion is held in by a two-bolt collar.
Thanks for the heads-up on using Corsa B (non-canbus) stalks. I see what you mean about the Corsa stalks being cranked towards the wheel... Hmmm.. rethinks plan to use Rover stalks
I take your point that 70amps may be overkill but a relay certainly looks to be the easy way to get the ignition-switched power to the fuses.
Cheers
Greg