Based on the version of Marvin the robot that you are using, it appears that you are basing this more on the British TV series (early 1980's) which was based on the late 70's British radio show and featuring much of the same cast that was on the radio show. This would actually be great news, at least IMHO. I loved the books, and felt the TV show did an excellent job of recreating the style and tone of the books (the fact that Adams wrote the radio and TV scripts and also made occasional guest appearances on the TV show also helped).
Yes, the TV show had cheesy 80's special effects, but I felt it was done SO much better than the movie. Frankly, to me, the movie was an extreme disappointment after having seen the TV series. I believe you can check out the TV series for free on YouTube.