Gosh, I read this yesterday and posted but it was deleted so will try again. I don't think the OP is being unreasonable in the slightest. Here we are two adults and two teenagers. An average spend in £150 - £200 and probably more if we have guests or people to dinner.
We eat well and yes, we eat a reasonable amount of fresh meat, fish and fruit and veg. From here the drive to the nearest aldi/Lidle could take up to an hour at weekends and there is no local street market. I also work full-time and there is no way I could "shop around" but factor this in as an expense of working although I do accept I could probably save £30-£40 a week if a I did and would if I had to.
Meals this week are thus: Sat: macaroni cheese, tear and share and salad, Sun: roast lamb and all the trimmings, Mon Smoked salmon salad and pasta with smoked mackerel, Tues: meatballs, pasta and salad, Weds: Chicken curry with thighs, lemon, spinach, creme fraiche, Thurs: beef stir fry with noodles, Fri: fish, chipes and peas.
Add into that lot, loo roll, cat food, cleaning stuff, shampoo, cond. shwr gel, listerine, yoghurt, bread, milk, juice, ketchup, beers, fruit, olive oil, cheese, bisbuits, cereal, tea, etc. and it all adds up. I will also add, that I do not buy the most expensive things on offer, keep an eye out for deals and often buy "essentials or value" ranges.
Teenagers eat huge volumes, we must do at least 9 washes a week, 28 showers and hair washes a week, 7-10 dishwashes a week and it all adds up.
Feel very tempted to say also that the last quarters gas and electricity bill was more than £800 and that is because we use the heating judiciously.
I once challenged myself and did the food on £50 for a week (DH was away). I bought nothing other than that which was edible and it was pretty grim. Do-able and nutritious but nevertheless grim.