SW1, first of all congratulations on your degree. I hope that you enjoyed your course and time at uni and wish you the best in the future.
I said it 'reeks' of a M.Mouse degree (note I didn't say it was!) as I work as a researcher at a US university (born, raised and educated in the UK, thankfully) and I see the UK system rapidly driving towards that in the US. At the core of it, US universities are a business, someone told me once it was the second biggest sector of their economy, which seems believable. Anywho, in a lot of instances departments start up fashionable degrees for a quick input of cash, especially if they are struggling with intake which mathematical or natural sciences generally do. Something pilot related seems like a good choice due to the prevelance of 18 yrs willing to give away mum and dads cash on this forum.
As far as I remember all degrees at public universities in the UK are accredited and held to the national standard by some oversight agency, the name of which escapes me, so anyone completing the course will have an accredited degree. However I would be careful when arguing "guilt by association" when trying to promote your individual qualifications. For instance, during my university career I have taken courses alongside chemists, but that doesn't mean I have a chemistry degree or even know anything about chemistry.
I would caution waving membership of 'professional' societies about. Your uni may have rubberstamped something, but that is generally just to say you are full-time student and you get a discount. It turns out for the two you list I am eligable to join; the IMECHE since I have a "UK Maths, Physics or other relevant Science degree" and the RAES because I have an honours degree and 66 quid. I'm not an aeronautical engineer.....
Call me cynical if you like, but I am privvy to lots of what is going on the university side of things and I have seen what can happen to people who go into a poorly organized and poorly taught degree. My comments are trying to help make people aware of the issues surrounding these new and highly specialized subject and make sure they consider what they are going to commit 3 years of their lives and 12,000 quid to. There are lots of choices out there so use your head and heart in the decision.
Cheers,
Gareth.