For beginners' purposes I'd suggest:
Developer : Ilfosol S - Liquid (easy to mix), available in 250ml bottles (recommended as it's cheaper and you don't have to worry about shelf life as much) from Jessops, Jacobs and pretty much everyone else.
Stop bath : Ilford Ilfostop Pro or Jessops own (Econostop?) - Brand and type not critical. Widely available in the high street.
Fixer : Ilford Hypam or Rapid Fixer (it's the same stuff) - It does the job, no complaints. Again, readily available over the counter. I'd get 500ml of this as it dilutes half as much as the Ilfosol.
Wetting agent : Ilford Ilfotol or Kodak Photoflow. Optional, but useful for avoiding drying marks. Ilfotol is usually easier to find over here and usually cheaper. (Buy a small bottle, a little goes a very, very long way!)
Film : I'd recommend Ilford FP4+ (ISO 125) or HP5+ (ISO 400). Both are very forgiving of errors in time, temperature and dilution.
See the data sheets on Ilford's website, especially the washing process (but note that Les McLean extends the number of wash cycles over and above Ilford's pattern).
All the best,