Australian sheepskin boots and a down (or down & feather filled ) jacket will keep you very warm. Woolly hat optional if you are 'seriously challenged' on top lol.
(serious about the boots and jacket though, didn't know M&S still did thermals ? Are they like longjohns hahaha)
All outdoor shops will have only PolyPro in PL and the prices are high. If you want old school woolies or cotton waffle long johns it is gonna be hard to find.
u can even buy pocket warmers if your that cold :) my advice mate is dress like your about to climb mount everest , the mrs told if was chilly so my advice is stock up .....