Measuring jugs, developer, fixer, stop bath, thermometer, timer (or watch or clock),
bottle opener for 35mm film, pegs or film clips, a darkroom or a changing bag, water, an exposed film...
A changing bag.
Either a film can opener or a film tongue retriever.
Scissors.
A large stainless steel salad type bowl (I use one of these to get water to the right temperature before I measure it into the jugs, got it cheap in Asda)
Three measuring jugs (one litre max capacity should be large enough, again cheap in Asda).
A measuring cylinder.
A small syringe maybe 20ml capacity for fine measurement of chemicals (you can get these in any chemists, mums buy them to give babies calpol!).
A thermometer, preferably a long glass one that can check temperatures right through a litre of mixed chemical (Jessops sell these if you can't get one on Ebay). Personally I wouldn't go for the digital thermometer because you can't stick it deep into a litre of chemical and stir it around to ensure you have the correct temperature.
A squeegee (this is optional, some people use them, some people don't).
Film clips (Jessops also sell these if you can't find them on Ebay).
That lot should get you developing film. Be warned: It's addictive and there is no cure!