With regards to the medicals:
I passed my NATS medical last week and I am off to Gatwick on Monday (Pretty short waiting time at the moment apparently)
The doctor did say to me that normally they will get you booked in for a course and send you to the CAA at a later date assuming your NATS medical went swimmingly.
I mentioned a head injury I sustained when I was 10/11 years old, and because I was concussed and sent to hospital the doctor decided that it would be in my best interests to pass the CAA medical straight away. He told me that this is nothing to be worried about either - if they had any doubts then he wouldn't be costing NATS ~£200 (+ travelling expenses) to have me fail.
He said it would stop me worrying about failing the medical when trying to focus on studying for the course if I got it out the way.
However, from the sounds of things, it seems that if you pass NATS medical with flying colours then they will put you on a course straight away. In the long run, it will be saving them money if they can keep your medical valid for a longer period into your "on-the-job" employment.