Swimming is during SEP, which is about 10 days into the course. Was a while ago now, so don't hold me to that.
The course is quite tough, and could be a little more organised, but it is only monday-friday, which is nice. Enjoy your weekends, because you'll miss them a great deal once your online.
Be nice and friendly, try to make friends and build a good rapport with all of the people in the group, and always say please and thank you to your trainers. Simple advice, but after 6 weeks of gruelling training, it is easy to forget the simple things.
Be prepared to study at least 2-3 hours per night. If you live far from Crawley, you need to think about moving down for training. Sitting in a car for an hour each way, will cut down alot on your study time.
Don't go out during the week, as tempting as it may be. And don't go overboard on the weekend. It is only six weeks of your life.