weselfluren,
Can't speak for NATS but Eurocontrol (from what I know) have a fairly streamlined procedure. Once you've been called for interview, it'sa matter of months before the pocedure runs its course, hopefully culminating in selection. To the best of my knowledge, the selection takes place twice a year .... it has been many years since I faced that particular hurdle, so that data may be out of date !
As far as reasons for or against the continental route, well, those answers have pretty much got to come from yourself. While it's not that far from home, it is radically different in many (perhaps critical) respects. Only you can be the judge of how much of an obstacle those differences are. Suffice it to say, there are plenty of us 'Islanders' over here who are pretty happy with our lot ! Since RYR are going to start STN - MST daily flights in a couple of months, if you're interested, why not drop over and check the place out?