I disagree with the two jaded individuals above. On the design, approval and airworthiness side, the industry is very busy and very interesting. Maintenance and operations are bad places to be at the moment, but the industry overall isn't necessarily. There is certainly a sorry lack of high calibre CEng level professionals across the industry and the money if not exceptional, is at-least as good as you'll get in the Automotive sector.
Your combination of presumably a CEng MIMechE, and a CPL probably gives you a good change of a job interview with one of the big companies - BAe / Westlands / BNG / Marshalls / FRL if a suitable MechEng / aircraft design job is going. But you do really need to understand some of the more highbrow theory that hasn't been picked up between your flying and MechEng qualifications.
I'd suggest investing in a handful of books. Start off with Darrol Stinton's first two books, "Design of the Aeroplane", and "Anatomy of the Aeroplane" (although the former is a bit hard to get hold off at present). "The Aeronautical Engineers Data Book", by Clifford Mathews has just come out, and is also worth having.
I'd also suggest buying or downloading the main airworthiness codes, JAR-23 and JAR-25 and learning your way around them, particularly the main definitions, the flight envelope, and the standard methods by which things are done in there. Megson's "Aircraft Structures for Engineering Students" is helpful in understanding some of the more aircraft specific stuff like hoop stresses or torsional divergence.
Finally a bit of the mathematical side of flight mechanics is useful. There are several books around on the subject, and I'd hesitate to recommend one beyond the others. I've yet to find a book that stood out to me as excellent, but neither have I found one that was truly appauling.
As to courses, there sadly isn't anybody in the UK doing distance learning AeroEng degrees, despite efforts by myself and others from time to time. Farnborough College does a good part time one, but you'd be better off looking outside the UK to somewhere like Embry-Riddle.
Noting from your profile that you're in London, you could do worse than stroll over to Imperial College or QMW who both do well regarded aero-eng degrees. Even if they don't do part time degrees, the bookshops are likely to be worth a browse.
Best of luck, designing, building and testing aeroplanes is a fantastically interesting occupation.
G