The wheels are in motion already for G8. My force has already asked for PSU trained officers to come forward to volunteer.
The pisser is that little if any of it will be for any extra money, as leave has already been cancelled across the force.
There is an annual leave embargo in place for the period for all officers and rest days have been cancelled already so that we (those not going to NI) can back-fill for those that are going at no extra cost to the force.
Personally I doubt whether any extra police a/c and/or crews will be going. Even they did I'm sure the met would be chosen to do it in preference to anyone else.