Geolocation iRule,

'string tolower' changes the country code to lowercase yet your switch statement is all in uppercase. Change to the following and give it a test:

when HTTP_REQUEST {

if { [string tolower [HTTP::host]] contains "marksandspencerme.com" && [HTTP::path] eq "/" }{

     Parse the client IP from the CDN header
    set client_ip [HTTP::header value "Client-IP"]
    if { $client_ip eq "" }{
         The header was empty/did not exist, so use the actual client IP
        set client_ip [IP::client_addr]
    }
    set country [string tolower [whereis $client_ip abbrev]]
    switch $country {
        "jo" -
        "eg" -
        "bh" -
        "kw" -
        "qa" -
        "om" -
        "lb" {
            HTTP::redirect "http://www.marksandspencerme.com/-${country}"
        } 
        default {
             Redirect all others
            HTTP::redirect "http://www.marksandspencerme.com/"
        }
    }
} else {
    pool Pool_www.marksandspencerme.com_2.54_HTTP
}
}

Are you look for the country or state? If country change the set country line to the following:

set country [string tolower [whereis $client_ip country]]