Just for some clarification Action Air competitions can and are shot everywhere NOT just at Carlisle, it just so happens the last comp I shot was at Carlisle.
The UKPSA is the UK branch of IPSC (International Practical Shooting Confederation), IPSC competitions are shot all over the world using REAL STEEL firearms AND airsoft, here in the UK we are restricted to airsoft pistols, real steel shotguns, .22rf semi-auto rifles/Long barreled pistols, full bore centerfire long barreled revolvers/bolt action/straight pull rifles in England, Scotland and Wales, and full bore pistols in Northern Ireland.
There is nothing preventing anyone from setting up and running Action Air comps at your local skirmish site, gun club, town or village hall, back garden or basement (subject to UKPSA membership/rules if you want to run sanctioned matches and be covered by UKPSA insurance.)
https://www.ukpsa.co.uk/
https://www.facebook.com/groups/1164767277044880
https://www.facebook.com/UKPSA