got 30+ punters up for a day out on a saturday in feb. looking for a good site somewhere on the 11 o'clock direction on the M25 - halfway drive-wise between M40 and M1 would be ideal. need to take these guys out for a top day so suggestions please. anywhere I can bring my own marker would be ideal to let some of them have a play about with it for future use - air availability an even better bonus.....suggestions please