The weight of damp soil is usually much more than folk expect. Do some research if you don’t want your planting to land on top of treasured senior aunts on the sofa (speaking as a senior aunt 😉).
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
To reduce weight use polystyrene in the bottom for drainage rather than gravel or crocks. Much lighter and also insulates against frost. Line the inside sides of the pot with bubble wrap to reduce water loss in summer and protect root ball in winter.
Posts
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
I think the following with be of use
https://mycontainergardener.com/plants-for-roof-gardens-growing-on-a-windy-site/
Hope it helps in your selection