Why does it have to cut down in autumn, and how big is the pot?

On the whole, annuals may be a better bet - they should grow quickly if you choose well, plus you'll be able to change year to year if you wish.
On the other hand, if you can store it somewhere warmer over the winter, this could be ideal for a tender climber. Maybe Campsis (which is fairly hardy), Tropaeolum speciosum (fairly hardy too, if a little fussy). My favourite in this section though would be Sollya heterophylla. Check out my photos of this at the link below. A perennial sweet pea would certainly get dense enough, although how well it would perform in a pot I'm not sure.

http://www.growsonyou.com/meanie/photos/sollya

The reason it has to be cut down, preferably every year, is that it is right against the road on the outside & a narrow alley on the inside. We did have a honesuckle there, but after a year it grew out into the road & nearly filled the alley !! I might try annuals for a year & see how they go, but I have made a note of your suggestions, thanks. Angela