Joe,
As has been alluded to before, if you want to be a pilot then go all out to be a pilot. If the RAF doesn't take you, make sure you explore all other flying options rather than become an EngO just because it gets you into an RAF uniform. (And please, don't believe anything along the lines of: "Well, join up as an engineer and then transfer later to pilot" - cross-overs like that are rarer than an honest politician)
If, and only if, you have decided that flying's not for you, then the life of an EngO is, in my biased opinion (with 15+ years doing the job), pretty damn good.
But it is not a hands-on job in terms of putting on overalls and fixing aircraft. (if that's what you want, then the non-commissioned route is better). Furthermore, at best, you will have no more than 2 tours at first line (actually on a flying sqn) in your entire career.
Essentially, the job is engineering management. This can involve being responsible for a large number of technicians (70 or so as a first tourist JEngO) or none at all. It ranges from having to make immediate decisions (Can the jet fly with a particular fault) or ones which will have an impact for decades (equipment procurement for example).
The range of employment is vast; in addition to what's been mentioned earlier I would offer: being a technical expert in the Defence Intelligence Staff, overseeing civilian contract implementation, working on exchange with other air forces, managing an aircraft fleet and running technical training courses. The list goes on.
Bottom line - I've always promised myself that the day I stop enjoying the life, I'd get out - irrespective of any short term financial issues. But I'm still in, with no intention of leaving. (hmmmm, but maybe that's just a reflection on my limited horizons...)
Whatever you decide, go for it balls-out and good luck!