Which plant to choose - not bamboo?

My partner and I are both not natural born gardeners. Here is part of my front garden.

http://picasaweb.google.com/lh/photo/rf5it3wp1evKGEZhBn7XXw?authkey=WK_5rqNjgTk

We want a plant outside that window, but since the garden is membrane-and-stones, it would go in a tub (half-barrel) that we've bought, which is about 55 cms high and 65 cms across. I have put down a couple of paving slabs to give some idea of where it might go, on reflection I think maybe further away from the window would be good. The garden slope down slightly towards the house, but nothing extreme.

The window faces slightly to the west of north, and we live in NW Kent.

My partner's suggestion was a bamboo plant, but down at the garden centres the labels on the type we liked said it grows to 5m high and 5m wide (though not in that tub, perhaps). I would welcome suggestions for an alternative which would fit the bill. My partner has shown no interest in what they have next door.

 

Beecee, there is no chance a bamboo is going to grow that big in a container. However, I would, personally, opt for a Musa Basjoo, a Japanese Hardy banana.:thumb:

 

Many thanks for the suggestion. I'll go and track it down, and see what my partner thinks.