Get the belt done ;) stuff breaks when they snap! Its not a bad job and theres some good guides on here how to do it. Give yourself a day if you never done one before, I got it down to about 3 hours now as my car had about 5 belts in 4 weeks but the less said about that the better, still trying to repress those memories.
I'd do the water pump too whilst your down there as they dont cost a lot and you won't wont to ever strip it all down again when you've done lol
Only tips I'd give, if you do change the crank pulley (axillary) as suggested, make sure the part is not made by 'BGA' or you could well end up needing a new engine in a few months time. If your motorfactor only has BGA pulleys, go somewhere else! Even when you have a non-BGA pulley check it is about the same as the one coming off....
Also if you get a water pump from Peugeot with the black metal type gasket, do not apply instant gasket as-well like people seem to do. It will more than likely make it leak! I applied mine without instant gasket and its bone dry
have fun!