Cold weather engine maintenance

[Walshie]

Hi everyone
The weather is bloody cold here in England but unfortunately I have to do some engine maintenance which obviously means opening the roof and folding the rear plastic window in.
I am carrying out this work in an unheated garage and I am worried about cracking the window or the stitching. Apart from trying to warm everything up, are there any good tips as it will probably be open most of the day
Thanks
Walshie