My new greenhouse

I have inherited a small greenhouse on my new plot. It's probably about 6x4' and made from very thin metal with big plastic sheets. Some of these have popped out or disappeared. Ideally I'd like to move it but I might leave it where it is and bodge it back together. Can you buy those plastic sheets anywhere? I was thinking of bracing the whole thing with wire to stop it bowing in the wind and popping the sheets out. Anyone tried this?

reading your topic I used a plastic type scaffold net very strong over my poly tunnel and braced it to the ground although we have had some strong winds its never moved an inch