ATC isn't like a lot of other jobs where you can get a generic qualification and then pick and choose from a wide range of potential employers. Generally you train with the company you intend on working for and it is not particularly easy to transfer qualifications between different organisations or countries as there is a lot of locality and unit specific training.
NATS only work in the UK, if you work for them (and are successful at training) you will earn the necessary qualifications to work as an ATCO for NATS in the UK. Some elements of that training may be transferable to another country's ATS provider but most will not and such a transfer is often strewn with difficulties and will likely involve more effort than it is worth. That is assuming that they will even be interested in taking you on, which is quite a significant assumption considering most European ATS providers are quite good at fulfilling their staffing requirements through their normal recruitment processes and don't often advertise positions for experienced controllers.
Find out who operates the airspace you want to work in and train with them... if it's Eurocontrol then just wait a few months, in the long run it isn't going to make a really significant difference and will certainly be less hassle than training elsewhere and then trying to move later.
Last edited by Pat42; 8th Mar 2010 at 12:44.