Had the tensioner pully on my vito van disinegrate today. Managed to crawl home with no alternator, water pump or power steering. Power steering fluid seems to be leaking from reservoir. Would that be caused by manually operating the steering? Im sure it wasn't leaking before

Yes it would .

I thought as much. Should be an easy fix. Now do i gamble on driving to eurocarparts before the battery dies or take the push bike....decisions!

Pushbike if not far and if you have a battery charger put the battery on charge for a few hours or more if you can so there's less strain on the alternator .