is it possible to remove the propane part of the HVAC and replace it with a wood burning stove? If so what would I have to change - eg the chimney etc etc?
It's possible, but unless your furnace is way over sized, you can't just stick a heavier box in the same packaging and burn wood in it. You can reuse the duct work and blower, but everything else would need to be replaced. Depending on how much heat you need, it may not make sense to place the fire box where your furnace is. Further more, you may want to keep the propane as a back up. Don't discount how convenient it might be once in a while to turn a valve, strike a match, turn a switch and have instant heat.
Heating 100% with wood in any cold climate takes a huge volume of wood. If you don't plan for easy transport of fuel from storage into the firebox, as well as good storage convenient to vehicle access, the scheme is doomed. Because of this, many serious wood burners have a boiler system to move heat from the firebox to the air handling unit (or directly to radiators). It's much easier to move heat stored in a fluid than to lug blocks of wood through the house and up and down stairs.
Consider carefully if you're ready for this. Every part of wood burning is dirty, hard work. When you factor in all the costs and effort, propane can be a competitive alternative. Another option many people take is to leave the HVAC system and install a wood stove in the main living area at a central location. The wood stove is capable of heating much of the house. The HVAC system is used to keep the outer rooms heated. This will typically involve re-balancing the duct system and moving the thermostat.
There's a lot of different possible solutions, what's best will depend on climate, house size, lifestyle, personal habits and preferences, etc. Locate contractors that specialize in wood fired heating systems, not just simple stove installations. It takes someone with that experience to make a reasonable recommendation based on your particular situation.