I can recommend Jo @ RideAbility too, top chap! (Sam on Gold/Brown Patriot) 🙂
A good warm up run is the green from the top of the Pleney, it is not all fireroad but is very badly signposted. Thanks to Jo I found it and my better half really enjoyed it. The trick it to go straight on over the small metal bridge at the end of the first fireroad switchback, it leads you into the the trees and some nice mellow (extremely quiet) turns and eventually out on to another fireroad. Take a left and follow it back to Pleney lift.
Bridge is at this point:
http://maps.google.co.uk/maps?q=morzine&hl=en&ll=46.166039,6.695883&spn=0.001566,0.003484&sll=53.800651,-4.064941&sspn=21.981746,57.084961&t=h&z=19
Jo may correct me on this though as its been a while…..