Sorry for the delayed response, ideally a commercial job would probably be the best then industrial just because you need three different type of wiring and three different types of containment, a commercial property has a good mix of industrial and domestic so you should be able to easily cover all the basis.
Regarding the fire alarm work I guess if he did quite a range of installs you might cover enough types of installation, iirc I had pictures of me making off a cat5 cable, but I'm not sure how hey would take not working around LV for your NVQ.
It is worth the investment having the Assesor write your diary, any of the lads still doing there's at the moment where pig sick when I told them I'd finished in such short time, it did help that I had already prepared with lots of photos over time because I knew I'd be doing the portfolio at some point, plus the fact I originally paid the smaller fee to write my own diary but I've got such a busy life at the moment I never seemed to get any time to start it and just bit the bullet and phoned up the college to pay the extra, honestly best move I made.
I'm time served but unfortunately, everyone wants a jib electrician, I've also worked for the same fella for 11-12 years so it's not been a bother, but now even the contractors want to see all the cards, and in my experience having a gold card doesn't make you a good electrician, but unfortunately it's the way it is and you just have to go along with it.