I think you have made a wise decision to attend and to answer your question the coroner does have the power to summon you to the inquest.
Hopefully you will not find your attendance to distressing, from what you say I very much doubt there will be a jury (there are circumstances where a jury is compulsory), it is quite informal, there are no strict rules of evidence, the coroner will ask questions of the witness and then interested parties may be given the opportunity to question the witness if they wish. As has been said it is not a trial, no one should be threatened in any way and you should not feel you or anyone else is on trial.