Ah, yeah that's the same e-mail I got, only I got the email invitation to the s1 test a couple of minutes later. It said I didn't have to do the online tests before I booked the date for my tests, but I had to do the online tests before going to stage one. Which it looks like I won't be able to do, but at least I've talked to someone at NATS about it.
Leaving tomorrow to head off to Fareham, I don't want to have to drive down there on Tuesday morning. So nervous!! Good luck grum123!