I am assuming (because you are talking pounds) that you are talking about Ask Jeeves UK. My experience is with Ask Jeeves US but the concepts are the same.
Basically you are paying to be included into the index (Paid Inclusion) on a per URL basis, for a 12 months subscription period. You will be listed in 4 to 7 days and re-spidered every 7 days or so.
You also get click thru reports and query terms.
With Ask Jeeves, you are not paying per click.
Remember that PFI doesn't boost ranking at all!
Warren