Obviously there CAN be good days in winter. They're just very rare and I've never seen one. Having your lesson cancelled due to crap weather is not going to give you experience of bad weather, it'll just annoy you.
Almost the whole of December last year was perfect flying weather (but yes, after that it was crap until April), and when you're flying it is wonderful with the kind of visibility you almost never get in summer. You'll cancel a lot of lessons, but not being able to fly due to the weather is part of flying in the UK and it doesn't change when your PPL arrives (it actually got worse for me, because I was over-cautious about my go/no go decisions. Still am). Everybody gets mad about it a couple of times and then deals with it.
