updated on 10 May 2011
Good on you for being proactive. Commercial awareness (a general understanding of the business world, and of what commercial law firms actually do and how they interact with other businesses) is where it's at! We don't know of any short courses, but, in fact, we're not sure that is really what you should be looking for at this stage. Rather, you need to begin to get a sense of the commercial world - mostly through keeping abreast of the legal and business press, and conducting your own research.
As a starting point, why not read back over some of the more recent news stories on LawCareers.Net to identify which topics are turning up again and again. For example, the Legal Services Act 2007 and alternative business structures, the Bribery Act 2010, and the economic landscape generally in the wake of the recession - think about how these things might affect a commercial law firm. Next, take a look at our Burning Question section, which is packed with articles about commercial awareness. The articles you'll find here are submitted by law firms, so it's the perfect place to discover which issues and pieces of legislation are currently in focus for lawyers.
Reading the legal and business press is of course vital too. In addition to financial press such as the FT and the Economist, you should be regularly browsing legal publications including The Lawyer, Legal Week, Law Gazette and RollOnFriday. For more about keeping on top of law and business media, see this previous Oracle, "Pressed for information".