There's a good bit of paddling in Manchester.I'd love a canoe but I have nowhere to store one, and in Manchester nowhere to paddle one
The ribble, irwell and mersey are all navigable (though some parts are arguably "private" - even saying that leaves a bitter taste) and as far as I know, are paddled quite often.
There's a fair few lakes and resevoirs that can be paddled close by too.
Have a look at this thread for some beginner's water in Manchester.
http://www.songofthepaddle.co.uk/forum/showthread.php?t=13230