After doing some searching, I found that if you go on http://www.itv.com/Watchnow/CatchUp/ , you can find a months worth of Corrie to catch up and other programmes.

Why this isn't highly advertised like the BBC's iplayer I do not know.

Though I did notice from watching the Christmas Day epic that it was advertised as a banner title on the bottom of the screen during the epic.  First time I've seen it advertised.

Come on ITV, if you've got this service up and running, you should be screaming it out to your viewers just like the BBC do.