Are you looking for just the normal tv channels ,say,freeview ?,if you are,then you can get that for free.
Just point your browser to
http://tvcatchup.com or
http://www.tvguide.co.uk ,under each freeview channel on tvguide (on the left side),you'll see "watch".Just click it to watch the live streaming freeview channel (soon they will be streaming HD channels too).
Free ,simple and dot on picture quality,can't get better than that and all down the same virgin media cable without having to take up any extra (paid )services.