Silver and Gold D of E are a must
Some people say the Gold D of E is worth an A-Level, in context.
Try doing something else may be schools aerospace challenge.
www.aerospacechallenge.org
I did it. Captained my team into winning it 2 yrs ago. £500 each too! Plus the fact it shows leadership, team work skills etc on your CV. And you get a week's flying at Cranfield.
My school didnt do it before I heard about it. Talk to one of your teachers about it. I had to set it up in my school pretty much all off my own back. Now they enter a team every year.
There's loads of other stuff out there too...
On Engineering side (& Im still gona be a pilot- but looks good on your CV, & develops character) try the Royal Academey Engineering Education Scheme.
If you want adventure; try Team 'World Challenge Expeditions'. Brilliant if you want to do gap year type stuff but dont wana take a whole year out- You can do this in summer between 6th form years.
RAF Air Cadets, CCF, Army/Navy Cadets, Scouts, St Johns Ambulance.
Make sure that when you go for a Job Interview, you stand out from the crowd!