Hmmm, I think I know you from somewhere - VATSIM I think
I've contacted NATS for some info, and from what I have received:
First of all, PPL is not required for NATS training. Everyone gets some "Air experience" of 15 hours - that's all. Not really relevant.
1) NATS places you either at a centre or Aerodrome control.
2) Plenty to spare ! From the official salary information:
On appointment for training £18,690 then on completion of Radar Rating - £19,592
After passing and you are positioned for Training & Development your salary is £27,952 rising to £31,734
On appointment as an ATCO (varies with unit) £35,828/£38,061
Rising to over £49,948
With prospects for £65,111
3) I think they would prefer younger people. Suppose it doesn't really matter. As long as you pass their aptitude tests.
4) See answer to 1) Not 100% sure.
5) As long as you have 3 Highers or above. Selection then depends on Aptitude test.
6) Couldn't tell you - perhaps someone more experienced could tell you.
Have you requested an information booklet from NATS - I did and found it quite helpful. Also got an interactive CD-ROM that has some more info.
Good luck,
Andrew M