Some new sizes of wooden greenhouses are now available. They are delivered in large sections which just need to be joined together. The panels are durable styrene so you don't need to worry about breaking glass when you are putting the greenhouse together, or when kids breaking glass when playing in the garden. (I remember as a kid trying to lock my sister out of my grandpa's greenhouse, and we were struggling with the door handle, me on the inside and sister on the outside, and the door slammed and cracked the glass. I think it's the one and only time i got told off by my grandpa.) So with styrene windows this sort of problem can be avoided!
The frames are wood, which as a natural material blends in well with gardens. Available in the grow your own section.