seems fine, but change the tin foil. It doesnt reflect efficiently nd insulates heat n keeps it in.
Do they actually still make tin foil in the UK?
In USA, it's pretty much, without a doubt, aluminum foil.
Aluminum (foil) is an excellent reflector. It's an 'insulator' of radiant heat, I suppose(this also means light, 97% or so reflective with IR). Not so much convected heat, and certainly not when it comes to conductivity. Though it has a very low IR emissivity(3%), but this only deals with radiance and not the rapid conductivity and substantial area allowing for convection to also occur rapidly.
When aluminum foils are used for insulation in homes they are most definitely paired with another type of insulation. Usually air and foam/fiberglass(which holds the foil). Air is a perfect insulator almost. Together they form an air/aluminum barrier. Where just enough convection occurs, and substantial solar radiation is reflected, and equally importantly the radiation from inside the home doesn't leave. Giving a cooler home in summer and warmer home in winter. Less radiance in, less radiance out.
All objects that you can visibly see emit all sorts of EM radiation, radiance, and also called light.
It's why when you put your hand close to someone else's hand... or even objects... you feel the 'heat'. This is radiance(and/or convection). Pretty cool, don't you think?