I did it last year - my thoughts would be:
don't stress too much - it's really not that different to buzzing around off leighton and surrounding beaches like we all do;
use a bigger kite than you might if you were just tooling about - better to be a little overpowered;
Stay upwind of the cargo ships you are bound to confront;
Use straps - it does get bumpy;
A twin tip or a surfboard will do just fine;
don't think about going to toeside - you won't do it on the day - you will just lock in and hammer. It's not really that testing. Just a little bit of work on the legs for a few weeks before - lunges and squats for example - and you will be fine;
Have a great time - it's an awesome day and a great experience

Cheers