I have a 1.5 kg frozen crown from M&S already covered in latticed bacon.
It's going into the fridge this evening to thaw, and then will be cooked on Christmas morning. Every site I visit seems to give slightly different cooking times - looks like about 1hr45-2hrs, then rest for 15-30 minutes. Hoping an expert on here will refine that for me a bit!
It shouldn't need anything else doing to it, other than bunging in the oven (no rack, so will stand it on thick slices of onion).