I was looking into the same thing, and found it very hard to get the address converted into lat/long details.
I came across a while ago of some blog, where some Dublin fella made a php script connected to some UK site that was doing just that, but couldn't find it again.
If you have any ideas let me know cause I am looking for a solution as well.
I remembered the script was using
Multimap.com - Online Maps to Everywhere
Aslo have a look at this:
http://world.maporama.com/idl/maporama/drawaddress.aspx