Janet Tweedy wrote:
Just an idea to run past the experts but would it be at all possible to
screw sheets of that polycarbonate stuff on the inside of glass for
winter protection? If I drilled holes in the sheets and screwed them to
the wood structure would it be better than bubble wrap which is a swine
to re use and clean.

The main insulating effect comes from the trapped air. If you want to
use anything else then the twinwall polycarbonate is the material of
choice. It is however much more expensive than bubble wrap.

The best tactic it to heat only the end of the greenhouse furthest from
the door and add a curtain in the middle. That way you keep most of the
warm air inside the greenhouse aginst the closed end.

Regards,
Martin Brown