Hiya Steve
Welcome to P8ntballer. As Rocket Rob says Apoc have a very active walk-on club. Apoc are on the A1198 towards Bassingbourn a mile just outside Royston. We have a sup-air team that can put out 2-3 team for a tourney and the 2 scenario teams. The walk on days are either on a Saturday or Sunday there is one this Saturday 13th Oct and the next 21st Oct.
If you are interested in Sup-air, training is on the 1st Sunday of the month. If you would like any more info on the sup-air team you can PM WooDzYo or Ahdinko on here who are the 2 team captian.
If you want any more help on the scenario side at Apoc I would speak to Rocket Rob who will be able to help you more.
Here is a link to the walk-on dates.
http://www.apocalypsepaintball.co.uk/joomla/apocalypse/index.php/walk-on-club/walk-on-dates
Just give them a phone call to book you in for the day and they will make sure they have enough paint on site.
They have a morning or afternoon session or you can play all day.
Regards
Ant