Irule Suggestion

Here's my untested attempt, using two datagroups, one that maps en:en_gb etc. and another that maps en:EMEA;

when HTTP_REQUEST {

 Remove any port specification from the hostname and store the result in variable 'hostname'
 set hostname [getfield [HTTP::host] ":" 1]

 Extract the third element of the hostname (reading from the right) and store result in variable 'subhostname'
 set subhostname [getfield $hostname "." 3]

 Stop processing this rule if the variable 'subhostname' is empty
 if { $subhostname equals "" } { return }

 Check if the variable 'subhostname' matches our data group list, if not, stop processing this rule
 if { not [class match $subhostname equals "dg_name"] } { return }

 Now we're sure we have a valid value for 'subhostname' let's move on

 Extract the country URI element as necessary based on the 'subhostname' variable value
 set salescountry [class match -value -- $subhostname equals "dg_name"]

 Extract the region URI element as necessary based on the 'subhostname' variable value
 set salesregion [class match -value -- $subhostname equals "dg222_name"]

 Now finally do the redirect
 HTTP::redirect "[HTTP::host]/SEUILibrary/controller/e/outlet_$subhostname/XYZPortal/$salescountry/special-offers.workflow:ShowPromo?LandingPage=/All/$salesregion/Portals/Outlet"
}