Take a look at my posting in the A Call for Battle! section of the forum. In my first posting, I list three sources. The first source (colonialwargaming.co.uk) lists both commercial and free rules for Anglo-Zulu warfare. From the second source (freewargamesrules.co.uk), I constructed a list of various free rules that I thought interesting enough to download. The last source (miniaturewargaming.com) had the free Lawks Drift rules and scenario by Henry Hyde.
My second posting lists the Colonial Adventures rules from the Two Hours Wargames site and also the interesting Patrol in N'Gululand battle report based upon the Colonial Adventrures rules that show how the rules capture the flavor of an Anglo-Zulu battle.
In summary, my first posting demonstrates that you can get plenty of free rules to use with the Wargames Factory British and Zulu plastic miniatures. In addition, the Colonial Adventures battle report leads me to believe that it is a modest cost rule set that captures the flavor of the period and provides for battles that can easily be played in a few hours.
If you find that your enthusiasm wanes, just grab your copy of the movie Zulu!, that first introduced the actor Michael Caine, and enjoy its presentation of the battle for Rorke's Drift to boost that enthusiasm. If you don't have the movie just wait for it to show up on television. It appears from time to time on both cable/satellite and free broadcast channels.