Hi Graeme,
If you use a Lesson activity instead of a quiz, you can do exactly what you are wanting. When setting up answers to questions in the lesson activity, you get to select where you jump to for each possible answer. Correct answers would be set to go to the next information or question page, while each wrong answer can be set to loop back to the same page or another page with an explanation of why the answer was wrong and then go ask the question again. When setting up the lesson, Handling of retakes would need to be set to 'Use maximum' so they could eventually wind up with 100%.
There is also a plugin, Content pages, (mod_icontent) that lets you present information and ask questions that allows for re-attempting the question if your initial answer is wrong.