How to Redirect Web Visitors According to Their GEO

[gordgoodfellow]

At the risk of this being in posted in too general a position on the forum (I thought of posting this in the Tracking section) ...

I run divorce affiliate programs which have three different merchants, according to where my web visitors are based (their legal jurisdiction), and these correspond to three different GEOs and three different affiliate programs which I'm signed up to.

My oldest established merchant client deals in cut-price divorces for people in the U.S. and Canada. A recent merchant client deals with divorces in the U.K. and a third (actually, prospective) merchant client deals with divorces in Australia.

What I'd like to be able to do is to redirect people at the 'Click Here' link to their constituent GEOs (possibly by IP address, or possibly by some other means) so that the people resident in the U.S./Canada got to the U.S./Canada affiliate website, the U.K. people go to the U.K. affiliate website and the Australians go to their affiliate website.

All in one click!

Does anyone know the best way - or the most reliable way - of doing this?