If you leave your body via HM Inspector of Anatomy for research, teaching or transplant, anything left over will be cremated at the Government's expense. That's what I've done. I like to think the ashes would go into my carefully nurtured 3-bin compost system but I suspect my wife would ignore my wishes if I go first and no-one else would bother. I notice that the grass and privet on the local church plot for the inhumation of ashes looks very healthy.
BTW It's only in the last couple of years that cremation has been legal in Greece,non-Orthodox families had to take the body abroad for cremation before that. In Orthodoxy remains are usually disinterred after a number of years, the bones washed by relatives (usually the women) and put in ossuaries. Thus frees up often scarce land for reburials. Orthodoxy has complex rituals at certain intervals after death,usually involving food and drink.
RtS