Hi MoonShadows
Many thanks to you for your detailed and helpful reply.
That's a great idea to lift it off the ground with treated timbers. I've yet to establish what the wood is around the existing structure and whether it needs replacing. There's going to be a trip or two to the timber yard.
I'll make sure that the structure is secured to the ground too. The garden, though flat itself, is located on the side of a hill, and it may be a windy spot.
I'm excited to be taking on the garden with its distinctive glass house!
Thanks again.
