As far as the forces at Rouke's Drift, B Company, 2nd Battalion, 24th (2nd Warwickshire) Regiment of Foot (2nd/24th) Did much of the fighting, but there were other units represented as well.
There was a small detachment of No. 5 Field Company, Royal Engineers, commanded by Lieutenant John Chard
There was about 100 Natal Native Horse (NNH) under Lieutenant Alfred Henderson,
(many left when the battle began)
A large company of the 2nd/3rd Natal Native Contingent (NNC) up to 350 men under Captain William Stevenson
(many left when the battle began)
The most of the battle was with about 150-160 defenders.
There was also a few units represented by the patients in hospital at the drift. By the end of it they had all fought as best they could, the wakling wounded were put onto the firing line to add to the defence. I hope this helps!