Andy,
You simply will not find a better made or priced jacket than the M65 field coat. It's one of those magnificent pieces of kit that are absolutely perfect.
65/35 cotton polyester on the M65 is done in a tight gabardine-style twill weave. It's very durable and if you treat it every so often with a waterproofing spray such as Grangers, you'll stay warm and dry in bad weather.
They have a hidden nylon hood in the collar, and if you purchase one with it's button in liner you'll probably even be too warm. Just make sure that you layer your clothing accordingly: base layer, thermal layer, and then the M65 as your outer layer.
My close friend Alex (brutha from a different mutha) has one, and I'm constantly trying to steal it from him. Go buy the jacket!
Adam