Robin, once you have completed studying for the Diploma, what do you plan to do?
A National Diploma is only good enough if you are planning to go to University or doing an apprenticeship or going to a 147 college. Even way you still have to carry on in an education institution before you be able to get a decent paid job in the aviation industry.
I completed my National Diploma in Aerospace Engineering Mechanical last year with triple Distinctions and I sometimes do wish I have completed an EASA license course instead. I am currently at a 147 college doing my EASA license and my job prospective looks much better then just doing the National Diploma.
PS. A National Diploma is a lot better than a First Diploma.