Tetrapanax papiefia 'Rex' (I think thats how you spell it) has great big jungly leaves and is hardy. Rodgersia also.
Paulowinia is a tree, but if you cut it down at base level every year it will re grow with huge dinner plate size leaves.

Depends how sheltered your garden is, really - an enclosed, southfacing one would be warmer than a northfacing, open one, so that said, and assuming it's more like the first than the second, check out Fatsia japonica, Phormiums and Cordylines. You will need to tie and wrap the Cordylines with horticultural fleece during the winter for protection, I'd imagine, and bear in mind the plain green ones are the hardiest.

Cannas are a easy, but may need storage for the rhizomes in the winter. Acanthus mollis is another possibility. Magnolia macrophylla and its kin may also work. Some of the hardier Yuccas, such as Y. filifera, might work in fast drainage, but they do have sharp tips.

i love my canary date palm.. i have a large one in the ground which I am hoping has survived the winter, its not looking good but I'm giving it a month to check! and a potted young one which I;ll take in during winter

... they make my garden feel tropical... have cordylines too
and running bamboo, which I am trying to transplant into pots as it has just broken through the barriers and is starting to spread... transplant not looking great right nowl and I am not sure how long it takes for bamboo to recover! any advice on that Molliejollie?