Sorry for your loss!.
I totally agree, tesco finest range is wonderful. Perhaps on Christmas Day itself, get the crown of turkey and pop it in the oven, it cooks quickly and there is no minding in it. Boil your ham the night before and this can go in the oven to bake along with the turkey. In Tesco at the freezers, you can buy frozen roast potatoes, these are delicious, while your at the freezer, pick up a bag of frozen veg that will be ready for the steamer or microwave and still at the freezer, grab Tesco finest chocolate cake with orange sauce - Sorted.
For the next couple of days, it is worth buying the baked potatoes with Chedder Cheese (also Tesco) these can be served with some quiche of your choice.
Also, get in some Knorr Soupfuls, they are a meal in itself. Be sure to buy brown bread and freeze it, take it out the night before or even that morning for it to defrost. Delicious and easy.
Do a list of food for each day and try to stick with it, it will help you remember what needs to be done and help ease the stress for you.
Marks and Spencers and doing breaded chicken fillets in bags of 9, ready to be popped in the oven. Serve these with salad, green beans, mash potato, which can be bought in Marks and Spencers ready made and it just needs to be heated in the oven.
How about buying some breaded fish, again no nonsense, on to a baking tray with some oven chips and 25 minutes, ready to serve.
I realise you want to make sure people eat at this difficult time and you want food that is easy but tasty. I hope the above gives you an idea of what may suit you and I wish you well in getting through your grief over this sticky period. Good luck to you!