Best central heating options

WaveWatcher

My In-Laws (70's+) are looking at upgrading thier heating system. They currently have a solid fuel stanly cooker for thier med-large 6 bed house heating c. 20 (+/-2) rads. They also have an open fire (backs onto the cooker in the kitchen) in the sitting room that also has a back boiler but it's rarely used. There is no other heat source. They turn the heat off for the upstairs unless some of us are staying.

The issue is that the cooker is 30+ years and on the way out, plus the daily chores around it like taking out the ashes and smoke escaping when re-stocking the fire or a blow-down are having a bad affect on my mother-in-laws already poor lung health.

We want something that is mininal effort with little to no smoke/dust and were considering an oil fired cooker (hard to get one to heat all the rads), a regual outdoor oil boiler, or pellet stove (heard poor reviews recently). The price of oil is putting us off the oil options just now. The kitchen is where they spend most of thier time so we need that room to be warm and we would be affraid we would lose a lot of heat be not having a cooker or stove in there. There is a radiator, but it doesn't heat the room same as the current cooker. The house recently had attic insulation and cavity wall pumped insulation done, but would still be a C or D rating. They are in the country so gas is not an option. The budget would be €5-8k.

Does anyone have any idea what would suit best or if our budget is even enough?

Thanks for any info you can give