Medical records were kept with the soldier's service record. So it is Ancestry for 1915. Few separate hospital records have survived. The local town/county record office will know. You should also enquire about Coroner records, as there may have been an inquest.
As a 'home' death you can always apply for a death certificate. If he had died on or near a battlefield the death certificate would have been a waste of money; as they just record 'Killed in Action' etc.
Ken