[Joe]

Hi Darren.
In terms of materials, you certainly have a definate advantage from when I did mine. It was pre digi days, so everyone spent a lot of their student loan cash on film and photographic paper (fortunately chemicals were provided by the uni).
As your portfolio should be quite an 'organic' showcase of your work, photos might want to come out and others included, so personally I'd steer clear of the fixed photo books and use the slip files, ring binder portfolios, or even niced mounted on foam core board in a box (I did this for a 'flat cap' portrait project, and it worked quite well for about 5-6 images, but got very messy when over a dozen were included)

In terms of subject matter, do what your interested in. However, showing a little variety helps show any potential course tutors that you have an understanding of different processes and techniques. Certainly, in terms of what you are being introduced to and developed, should reflect in the portfolio you build up. Doing your own thing shows any potential degree course recruitment interviewers you are able to 'develop' (pardon the pun).
Try to use a darkroom / photoshop technique to enhance the image to what you want rather than blitz'ing an image with different adobe plug-ins for the sake of it, unless you really wanted to get questioned why you did it by an eagle eyed tutor (and they would spot it too).....I guess it's the same theory as a word document, which you wouldn't use a different font design and size on each line if it were your CV.
Back then I'd taken some shots out and about and studio based that were in the style of a number of my favourite photographers, but then had a few more of my own projects. Ultimately, doing different shots also helps find what you are comfortable with and what you might not. Take plenty
Get as many picture minded people looking through your work. Quite often a fresh pair of eyes can make all the difference, whilst brothers, sisters, aunts and uncles might just say "they look nice"..which is all well intentioned, but not the greatest of help to you.

Does this help some?
good luck