You are very brave taking on Douglas Adams, even Eoin Colfer didn't manage that unscathed, but putting that aside I think you need a bit more structure to your story as the 'surprise' of finding Arthur Dent is not really a surprise if you consider all the other places he turned up in and the years he spent bumming round spaceports. Unfortunately your idea about illegal money gets somewhat lost. You might want to check your reference to Slartibartfast, he moved on and it was the dolphins who replaced Earth. Having said that, you have some great ideas and the setting is promising.
I recently started re-reading Hitchhiker's Guide to the Galaxy and at prompt group wrote about 'the earht people pushing green pieces of paper around'... more
oryx25