Who knew there would be a shortage of greenhouses?? You probably have Covid to thank for that, all the new gardeners!
I have a 'Brown Turkey' fig tree...bought about 5 years ago from a garden centre for £15. I had 136 figs on it last summer. We have one as well, get about 200 figs on it each year (yes I count them too). W Yorks at about 400ft - a bit warmer than where "Happy* is but if you can grow them in Teesside, Cally, then Happy should be able to grow them outside without taking up precious greenhouse space.
My father has a twinwall polycarbonate greenhouse - it's flexible rather than rigid (maybe it's not polycarbonate but some other plastic), so feels less robust than a glass one, but it's been standing happily for 15 years. Feels a bit warmer than glass, too. But you can't see into it from outside very well.
I've got a Robinsons which has been going strong for 30 years, but they cost an arm and a leg. I can only imagine that the cost paled into insignificance beside the cost of the house at the time we bought.
I grow cacti, tomatoes, cucumbers, and oddly, courgettes because it is a slug-free environment. I use it to overwinter tender plants that are outside in summer, for raising seeds (easier than a windowsill because the light levels are better) and nurturing small plants.
One us that hasn't been mentioned yet is that if you garden because you enjoy it, then a greenhouse gives you somewhere you can garden when the weather isn't conducive to enjoyable gardening.
I also have a couple of comfy chairs in there - it's my sanctuary.