I think that in the end you pay for your own medical (if you pass stage 3), so if it worries you I guess you can go and take the medical now. If you pass you can go on with the application process and you don't have to be afraid of failing the medical if you go all the way through.
If you don't pass stage 3 you will have lost the money spent on the medical, but that might not be to bad in order to be able to relax.
Don't take this as 100% granted though as the source that says that the medical is payed by us is not NATS themself (even though he is a NATS employee).