If doing a lot of work to the property and garden, I'd consider laying the loops in the garden and UFH loops in the house to make it easier to install in future if you want.
How about a coal stove(s) with back boiler? Also air source heat pump/air conditioners which will work well in all but the coldest weather.
Last time I looked, electric heat was 2x the cost of coal using Phurnacite, which was in turn 2x the cost of natural gas or air source heat pumps.
So in a rural location with no natural gas I'd consider air source heat pumps, with coal stoves for the coldest weather and as backup.
Once the weather gets to the the point where the heat pumps are operating at 50% efficiency then it makes sense to use coal instead.
If getting a few air source heat pumps then don't go for cheapo ones, an air con supplier should give a good deal on some decent ones.
cheers, Pete.