snuggly my mum used to steam frozen mixed veg and serve it to us on the side of main meals. I loved it. Also you can get frozen veg like corn on the cobs. Luckily DS loves peas. we use frozen fruit for crumbles and smoothies. But never defrosted them - that's a good idea. We have the same predicament with fresh fruit & veg. I tend to buy fresh carrots, cucumber, baby tomatoes & courgette. I used to buy loads more but it was getting wasted and was so pricey.
I find bananas, pears & apples last well in autumn / winter. We store the apples & pears in the fridge and fill the fruit bowl periodically so it stays fresh for longer.
We did try frozen broccoli which was really good when steamed. And frozen spinach for curries. Which both worked well. We found we were wasting potatoes (the type you roast). Not Jackets. So we started buying frozen roasties and that's saved us a fair few ££ over the weeks.
Sweet potatoes seem to go off quickly in our house but I still buy them. Maybe I should try frozen sweet potato wedges.
I also think you're spot on with your Xmas ideas. We bought DS very small gifts for his first 2 Christmas's. He was more excited about the fairy lights than any gifts. I think you could definitely wrap up some clothes. We wrapped up some toys that my DN donated to DS (DS didn't give a hoot at that age anyway).
We have also found that we tend to automatically binge buy food & alcohol for Christmas. It's silly because usually we are all fed well and too full up to eat anyway. We wasted so much last year.
We have started to buy 1 item for Christmas in our food shop. Like juice, stuffing, Pringles, fancy hot chocolate that was on offer & foil. It all helps come December. I think the price of foil shoots up in December.