How about considering a curtain pole from somewhere like B&Q. I broke one of my boathooks a couple of years ago, in France, and replaced it with a curtain pole, which has served well ever since. /forums/images/graemlins/smile.gif
(1) Curtain poles tend to have joins.
(2) Try Robbins in Bristol (they do deliver) www.robbins.co.uk archaic website but they do supply lots of species.
Try the local farmers shop. They sell replacement shafts for hay forks and the like. Nearly all their stuff is cheaper than chandlers! I have ash on my boat hooks, strong but heavier than curtain poles but do float. Not much point in trying to put a plastic hook on the ned though, get the galvanished/brass real job. It'll last you years, and float verticallly - easier to pick up when lost overboard!