Here is a sneak preview of StrikeForce Badlands, located in Abingdon in Oxfordshire. They have a game set on the 29th of May but do visit their Facebook Page to get further confirmation on this play date... "Play airsoft on an active military land warfare training area! approximately 140 acres of military training ground for skirmish and battlesim."
You can book your slots at Swindon Airsoft.