Welcome Hoggy and congrats on the Morgan
I have often thought about your situation ie buying a Mog in Winter with a limited time warranty
I can only think the advice given is the best and that is to check that all your fluids are suitable for Winter including the windscreen washer and get out in the car as much as possible
Last Winter I became a bit too saltaphobic so this year I'm making sure I get out when it's reasonably dry even with grit on the roads as clear nights and days tend to be cold
I'm just avoiding wet and salt as it takes a bit of hosing off
As Budster quite rightly says - Winter drives can be magical