I wouldn't bother personally. I bought a 8 x 6 foot pop up poly house this year and it lasted 6 weeks. I could never have the door open in even the slightest breeze as it would rock about quite violently and in the end, it fell foul to a gust of wind which took it over into next doors and completely ruined it !!!!!!!

never again.

I have three plastic greenhouses - all heavily weighted down with large stones at the base! (THAT was a learning curve!). I overwinter seedlings in two of them, both of which have TWO covers for extra seedling protection. One then becomes my 'Basil Factory' for summer so I can make pesto. The third one is my 'pots and bits' store. I have had them for four years and now couldn't manage without them. The two 'working' GHs are partly protected by standing against walls. If extra cold weather is predicted, I stuff bubble wrap between the two covers which adds even more protection. All of them are clear plastic.

Maybe a cold frame would be a better option, the tiny plastic ones seem always to be too hot or cold, and and Andy says very unstable

I have a 4 shelf growhouse, and that took of with all my bedding plants in in the spring, I now load the bottom shelf with spare cans of water or bags of sand.

I weighted one down with a concrete block. The top blew off leaving just the base behind!! (Only fair to say I'd used them before for some years without disaster)

Thank you for your comments. I think I'll try a cold frame first.