the summer series trials are spot on you will all enjoy them. enter clubman B thats the easies route. get your mates to join the acu before they go and i believe you can join the club on the day as the summer series trials are closed to club but the trials are a bit cheaper than normal center trials so you make the club membership back in a few trials. and if you ride 4 of the 5 events you qualify for a award at the end regardless of where you finish, so you can go to the awards night (another good do they put on). the summer series venues are good the CofCs are very experienced and all trials or ex trials riders and they even have a buttie wagon there for a munch before and after ( very important in my book), what more can you ask for. turn up and enjoy it and why you are there ask about there one lapper a very very good trial/day out.
see you there mate. Paul