You could probably thaw the turkey in 24 hours in cold water, but if you intend to thaw it in the fridge, it takes a lot longer. Depends, of course, on the weight. 8 to 10 pounds would take 2 to 3 days and 12 to 16 pounds 3 to 4 days. In cold water, changing the water each hour to keep the surface of the turkey cold, 8 to 12 pounds 4 to 6 hours 12 to 16 pounds, 6 to 8 hours. a crown would take around 4 to 5 hours if it weighed, say, 6 to 8 pounds.
As far as cooking, first let me say, here in the U.S., a crown would probably be the front half of the turkey consisting of the breast (with bone in), wings and backbone, the legs having been removed. Main thing is to keep it from over cooking. This is where an instant reading meat thermometer comes in really handy. A rule of thumb is 18 minutes per pound at 350 degrees F. (Did I say I was in the U.S.?).Tent the bird with aluminum foil until the last 30 minutes. Remove the foil and brown the skin. A good thermometer reading (inserted deep in the breast but not touching bone) would be 165 degrees F. If you stuff the bird, the stuffing should reach 165 degrees as well.
We like to gently lift the skin over the breast of the thawed bird and insert several pats of butter before roasting.
If you get adventurous (not recommended for first time at fixing a family holiday dinner), brining the turkey produces great results. Check here:
Ingredients
2 gallons water 1 1/2 cups canning salt (not table salt since it has added iodine) 3 tablespoons minced garlic 1 tablespoon ground black pepper 1/4 cup Worcestershire sauce 1/3 cup brown sugar
Directions
In a large bucket or container large enough to hold your turkey, mix together the water, salt, garlic, pepper, Worcestershire sauce and brown sugar. Store in a refrigerator, and soak turkey for 2 days before smoking or roasting. Roast as usual...
Best of luck!