The Coroner will question a witness first. After that you (and other 'interested persons') may ask the witness relevant questions, or your representative can ask questions on your behalf, if the Coroner agrees.
When asking questions you must remember that the purpose of the inquest is to establish the relevant facts of the death and not to apportion blame. You should not ask questions that appear to blame someone for the death.
It may help you to think about the questions you want to ask before the inquest, and perhaps send them to the Coroner in advance so he or she has time to consider them.
It is the Coroner who decides whether a question is relevant to the inquest. The Coroner will also warn a witness that he or she does not have to answer any question which might lead him or her to incriminate him or herself.