That's not a stupid question at all. Yes, you can. You can also use what we know as bubble wrap to provide an insulated inner air space. It can be worth the effort. I'd suggest you check with a local garden club or some locally experienced allotment gardeners (whatever is possible there) for input. Someone may be willing to help you get started.

Regarding the time and effort to establish the raised beds you mentioned a few posts back, You could be making piles gradually starting right now. Just start with a few layers of newsprint (black and white), topped with available compost, soil, straw, manure, soil amendments, coffee grounds, etc. on top of the places you reckon you'll want them to be. Never mind shaping or perfection; just get it started, then keep adding to the different piles as you have time and finances. By the time you are ready to really focus on the raised beds you'll have done much of the hard work already.