Space, like a second sentence, can be big, confusing and needs going through twice to really understand it. One of the few ways to comprehend how big space can be, is to be subjected to the total perspective vortex, but as this usually leads to death unless your ego is as large as say, Zaphod Beeblebrox's, it is just as well to accept everyone's word that it is. Distances can therefore become ridiculously large, large enough for those tired with light years (and the enormous slide rules needed to calculate in light years) to invent new, exciting words for inexorably large distances. A Kirpcatorno is now widely accepted as a pretty long way (say 23474 to the power of the collective ages of those at a reasonably successful party) and an 'Omp' is about twice as far as a 'Kirpcatorno.
However, to prevent distances getting too conceited about their sizes, ships such as the Heart of Gold or the Starship Bistromath were designed to sprint through space fast enough to make distances go into a corner and sulk. So for Arthur Dent to say 'We must be in Zaphod Beeblebrox's neighbourhood' when it is, in fact, 36 omps away, is not entirely unreasonable for a good hitchhiker.
To recap, Arthur Dent, having found a wonderful companion in Fenchurch (that being her name, not the place) had visited God's last message to his creation, only to have Marvin die in his arms. Ford Prefect had resumed his job as a researcher for that truly wonderful book, The Hitch-Hiker's Guide to the Galaxy, with new vigour and was probably skulking around some seedy bar trying to talk somebody into buying him a drink. Zaphod Beeblebrox had settled down with Trillian to raise kids and have a peaceful time not saving the Universe. In fact, although saving the Universe again was the furthest thought from all their minds (about 421 omps), it was preparing to renew its acquaintance with them quite shortly.