It should be available on the wonderful BBC iPlayer website for a week or two after showing on TV.
http://www.bbc.co.uk/iplayer/
The length of time programs are available on iPlayer varies (due to copyright issues I believe), but is at least a week I think. iPlayer is only available in the UK, and for me only works on Internet Explorer (which I otherwise avoid like the plague). iPlayer's a fantastic thing, worth looking at for other programs besides this one.
I've hooked up our living room PC to our telly, so it's just like watching regular telly except the picture quality is better (we live out in the sticks and don't get brilliant TV reception). If you have a newish flat screen telly it could well have a computer input (VGA [usually blue plugs on the lead] or better DVI [usually white plugs]).
The downside is that you could end up spending to much time watching telly.
John