In reply to idiotproof (Buxton MC): Anything will do.
I'm your size and have multi day toured on 1st generation fritchis.
Wide is generally better but wide has arrived later so you'l probably get
something 70-80 mm. Wide powder skis are unlikley to be relevant in the uk so no problems there, and the reality is powder is usually not the hardest skiiing you'll do on a tour.
Skking is massively consumerist but you can cheaply get kit that will match your boots and ski anything you like.
have fun