You can buy ready made/mixed chemicals from a variety of sources in UK. Just have a look on the web. I suggest AG Photographic, Fotospeed, or Firstcall Photographic. These people will supply a kit which contains developer and the bleach fix for a number of films.

The standard development time for C41 colour negative film at 38 degrees C is 3mins 15 seconds. As far as I know all colour film developers are the same time for the same film. Temperature is fairly critical and any deviation from the 38c will not give you optimum quality. If the Film you are talking about is not C41 type, but C22 then you will have to look further