been reading all of the above and........
if flying is really what you want to do, then I would put off the masters unless you can get onto the course without graduating from your bachelors degree.
i am doing a masters in aero engineering, but only decided upon it as the airline jobs market last year was dire, and my department allowed me to step up from the 3 year BEng to the 4 year MEng without graduating (i.e. still get support from the LEA/Student Loans and the tuition fees are only £1100 rather than closer to £5K)
As for increased earnings, I have found that the majority of the places I have applied to for a graduate job (to fund my flight training) are only offering between £500 - £1000 extra salary per year for having the MEng rather than BEng. As I only intend to be in industry for the duration of the time it takes to get a flying job, this wont cover the approx £7k extra its costing me (fees + loan + living expenses) to do the extra year.
However, the best thing about the masters route is that you are getting a higher level of education, and that many employees (the ones i'm speaking to anyway) regard a 2.1 masters as the equivalent of a 1st class bachelors. you also have evidence of committing yourself to the course, which the airlines may look favourably on when applying for a cadetship.
also (and this is the best reason for another year).......................................
.CHEAP BEER AND EASY WOMEN!!!!!!!!!!!!!!!!!!!!!!!!!!!