Adding a 'Blogs' section to a magazine style site

I’m running a club website with the Arras theme which makes it more of a ‘magazine’ style. At the moment we’re using it to post news, events, profiles etc, but I’ve been asked to provide a Training Journal section.

The idea is we’ll be able to add individual user accounts for our students and give them their own training log. These would all be grouped under one heading of ‘students training logs’.

My question is, what’s the easiest way of doing this? I imagine what I need to do is add a new category (something like ‘student blogs’) and have every entry automatically entered under this category. I could then add a menu entry for that category, and hopefully child menu entries for each user’s postings? How do you automatically choose a category for a user’s posting to override their choice, or ideally not even offer them that choice.

Thanks in advance.

The website is http://www.cornwalltangsoodo.co.uk by the way, in case you wonder what I mean.