OK, one possible setup (and assuming both my math and memory are right, neither of which is certain):
Planting Douglas Fir, which is fairly fast growing (one to two feet a year) and a good wood for lumber and for burning, planted around 16'-18' apart (or half that, and thinned as they grow). They become large enough to be commercially valuable at around 30 years; at that point, they will have a diameter of somewhere between 16" and 21"; I'll be conservative and say they're at the low end, at about 16". That gives you half a cord of wood per tree (18" will get you about 2/3 of a cord, and 21" will get you almost a full cord).
Go to the National Ag Safety Database and look up "Home Heating with Wood" and determine how many cords you need, given the size of your home and the type of stove(s) you are using.
Once you know how many cords you are going to need, multiply that by 2 (2 trees per cord), by 30 (years to grow a tree), then by the feet apart you plant your trees squared (square feet per tree). Divide that by 43560 (square feet in an acre). Add a little more for a safety margin, then add a lot large enough to hold your cutting area plus enough land to hold a year's worth of cut wood for seasoning.
That's how much land you need.
I would suggest you talk to people in the area you plan to move to in order to determine the best woods to grow in the area, how much space they need, how long to harvest and size at harvest, etc. to get an idea of what's reasonable locally. Also, the size of and insulation in your house will make a big difference.
Note: (From Wikipedia) The cord is a unit of measure of dry volume used to measure firewood and pulpwood in the United States and Canada. A cord is the amount of wood that, when "racked and well stowed" (arranged so pieces are aligned, parallel, touching and compact), occupies a volume of 128 cubic feet (3.62 m3)