Gaffer Tape said:

In fact, they should change it so that the pod destroys the second Death Star. ^_~

All kidding aside, I always sort of assumed Jabba was somewhat close by. Maybe the same planet, maybe a nearby planet that could be reached fairly quickly. That, or the "I was just going to see him..." was more of Han's BS to buy some time (most likely the case). Truthfully, Han just wasn't a good guy, regardless of what Lucas tried to SE him into decades later. The character worked because he wasn't a good guy.

Even though it isn't everyone's cup of tea - in the NPR radio version, Han is much more of a shit than he is in the film. In fact, he's truly unlikeable for the first few hours, and not in a cool, rogue sort of way - but in a selfish piece of crap sort of way. He fully intends to leave Luke, Ben, and the princess on the Death Star.