I'd say provided its legal (i.e within planning / building regs) then go for it. Other than some diy skils i'd never done much building work before 3 years ago, when along with my dad and brother we thought we'd have a stab at building a 60 square meter extension.
We ended up hiring a brick layer to do some of the birck laying, mainly because we'd still be doing it now if we hadn't, but other than that we did the rest ourselves, and have been living it it for a year now. - It has all been signed off by the building inspector.
We learn't a hell of a lot from doing it, and overall it was good fun. It also saved a fortune compared with getting a professional in.
Best of luck with the project, just work through it one bit at a time and there's not a lot you can go wrong on really, provided you research it first.