Not sure if they'll have what you're looking for Janie, but Harrod Horticultural do quite a few greenhouse fixings etc. Scroll right down the page, most of the bits are near the bottom.
Greenhouse Equipment

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Sarah

“Tell me one last thing,” said Harry. “Is this real? Or has this been happening inside my head?”
“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?”