Iceweasel is making me feel stupid! I simply cannot work out how to add google.co.uk to the list of available search engines. Well not in an easy way anyway. Google UK isn't one of the engines I can choose from the drop down but I do get the option to 'manage search engines'. This lets me order the existing engines sends me here to add new engines. This lists a handful but not what I want. In the end I resorted to hacking one together myself. On my Debian install, search engines are stored as fairly simplexml files in the folder /usr/share/iceweasel/searchplugins. I found a file called google,xml in that folder and made a copy of it called google-uk.xml. I opened it an editor and making an educated guess as to how it worked, I changed the shortname value from 'Google' to 'Google UK' and replaced all instances of 'google.com' with 'google.co.uk'. Happily, after restarting Iceweasel, my hacked Google UK engine was available. There must be a better way to do this but for the time being this has scratched my itch. The xml format is properly explained here.