So satisfying seeing your growing space safe from the weather.
Forgot to ask, is it in the garden at home?
If it is and if you can afford it, I thoroughly recommend running mains electricity to it and fitting an outdoor switch & light and a double outdoor socket.

Properly done with armoured cable etc isn't cheap.
Then get a couple of Stewart heated propagators and a really cheap growbag "greenhouse".
Put growbag jobbie in glasshouse and fit one heated propagator on its bottom shelf.
Ideal seed germination, that warms a twin shelf seedling area, before hopefully adding some frost prevention to the glasshouse.
Second propagator for stuff that needs better light.