Why are you asking OcUK? Get the yellow pages out and do some calling!
Looks expensive! Organise to have it replaced yourself rather than going through the letting agency / landlady as they will likely charge more
It's not going to suddenly shatter is it and fall on the cat?
It's double glazed and only the outside pane is shattered.
If you go directly to an industrial window manufacturer they'll probably sell you a double glazed unit. However you'll need toughened glass so the price will be slightly higher. Can't remember what we used to charge but I'd guess you should be able to get it for less than £100. At the place I worked at one of the guys would come and fit it for £50 at the weekend.
Looks like some young hoodlums have vandalised your patio door!