Yeah, just try to blend in and dont draw attention to yourself. Make sure you drink lots of water while the medicals are taking place as you could be waiting for up to 3-4 hours in a shitty hot room, i diddnt drink and my physical scores suffered badly. Watch out for the PTI guys , Apart from that just enjoy it mate.
While i was at Lichfield in june, there was about 25-to-30 blokes, only a few failed, just go, work hard and enjoy it.
Quick hint: For your room inspection make sure everyones bed in the room looks the same, even if a bed is empty.