1] The country code which is recieved from geoip_country_code() needs to be stored in a cookie.
2] Before the redirection runs the script should check if a cookie exists. If cookie exists it should redirect to the address stored in the cookie and not run the redirection script. If the cookie does not exist then it should run the redirection script and store the country code and redirection url in a cookie. The cookie should have validity for 90 days.
3] Also a dropdown must be created with the country names in the same html file. After redirection from the redirection script if the visitor manually selects a different country the original cookie should be replaced with a new cookie with the user selected country code and redirection url should be stored.
4] Next Mod: eg. If a user from "US" is visiting a "UK" or "AU" site for the first time with no cookie stored he should get a modal window prompt informing to select "US" or go ahead to "UK"/"AU". This applies to other country sites as well.