but don't forget that there is also EuroControl (in Brussels)
Eurocontrol Upper Area ATC centre is located in Maastricht, NL. Brussels is the HQ and also Flow Centre (CFMU) but these are not for you if you want to talk to the big jets.
Whatever you decide, good luck with it, its a great job well worth doing, not many who do the job regret the day they applied.
Also, it is well worth taking the bull by the horns and organising visits to Centres or Towers, and talking directly to people who work there. As well as an informative and interesting (we hope) visit, you might also get contacts within NATS who could advise you further. ( I only say NATS 'cos you're there already, I guess flying to Maastricht for a visit would certainly show a keen interest mind you!!)