We moved to an oldish (approx 150 years) house last year, with a 30+ year old oil boiler and Aga that did the water. There wasn't anywhere for alternative cooking to be able to switch it off in summer (you could switch the water over, so that wasn't a problem), and we were burning so much oil keeping the Aga on, it was frightening.
In the end, we installed a new, efficient boiler (moved it outside as well, so freed up space in the utility room), and removed the Aga altogether. From having to fill the oil tank every 5 weeks, I had it filled just when the Aga was removed, and we'd only used half in nearly 6 months (granted over the spring/summer months, but SO much slower than before, the Aga clearly had a drinking problem).
We installed a couple of new double radiators in the dining room to replace the lost Aga heat, and they've been great.
We looked at a variety of things, and nothing really worked unless we were doing a house renovation, tearing up floors etc. We looked at wood pellets, but we would have basically had to lose our massive garage to the system, and as said by PPs, been all over it to keep it regularly topped up. No gas in our village, a £330k charge (yes really) to get a connection, oil cheaper than LPG.
Longer term, hopefully options will improve, maybe by the time we need to replace the boiler again...
But no regrets on losing the Aga at all.