I know some engineers that are still doing hands on work, 35 hours a week earning £100k a year with a B.Sc. I know PhDs sat at the next desk to someone with an HND (high grade technician qualification) and with similar experience, however the PhD earns less as he is neither as good or as hardworking. The qualifications really don't make much difference a few years out from university.
To quote Aleister Crowley, "Do what thou wilt." Unless you want to spend three years living on a crap grant whilst playing with physics, go and get a real job.