Most the major channels do a on demand service that will let you watch most programmes an hour or so after they are shown and there are a few specialist ones that do certain live events streamed (like GT1 racing) but don't think you'll find any that stream live TV.
There's a company called Veoh (I think) that do live UK TV streaming, although it's subscription. I had a free trial a couple of years back and it was good.
Hi, thanks for your replies.
I have been told about Zattoo http://zattoo.com/
and I have tried it, it's better than nothing but not that reliable.
cheers