hmmm so lets say I eat meat which I dont.
you want me to get the 2-3 buses there and back to a aldi to get1.5 kg joint of pork shoulder £4.21 plus £3+ for travel.
you want me to shop in morrisons for the Potatoes (Wonky Morrisons) 25p which I have never seen because morrisons rarely actually have any of the wonky veg or fruit in, and I go there about once or twice a week after taking my kid to school, the last wonky thing I saw in there was the wonky mangos which I did buy 3 for £1.65 about 2 weeks ago.
Parsnips - roasted (Aldi) 20p again dont have one never been to one as far as I known the nearest is 2 buses away maybe 3, never been there, Carrots - boiled (Aldi) 15p, swede - boiled (Aldi) 20p.
frozen peas (Morrisons) 30p if you say so never noticed any that cheap in there unless your talking tinned.
Stuffing made from leftover bread, half an onion and herbs from garden. 15p, dont have a garden, you have not factored in the price of bread and an onion and are assuming someone has those things anyway (I dont buy sliced bread, only flatbreads normally)
Gravy - made from meat juice, plain flour, veg water.......10p, how is it ten pence, you need to buy a bag of flour thats not 10p.
so for you with the shops you have in your area and how they are regularly stocked it costs that much along with what you have in the cupboard normally, that doesnt make it the same for everyone.
and then theres the price of gas and the assumption you have a cooker large enough for all that, my oven has 1 shelf and the max tray size it can take is the IKEA konics 34x24cm tray.