We shop every week at costco and top up at supermarket for the stuff we can't get at costco.
Stuff lasts longer and is generally cheaper. You are probably still paying £2.10 for 6 pints of milk whereas I am paying £1.60 We go through 12- 18 pints a week so it is a big saving.
We eat a lot of peppers so we can buy a 6 pack that works out at 49p each whereas in the supermarket they were 88p each. A bag of salad is about 3 times as big but lasts longer than the supermarket. Strawberries are delicious and flavoursome and come in a 1kg tub. I laugh in the face of a teeny punnet from the supermarket.
Also we buy a huge tub of cherry tomatoes, they are as firm 6 days later, we use them up in spag bol or a curry the day before we go back to costco but they are still perfectly fresh.
Toilet roll - tesco own brand worked out to the same cost as andrex triple velvet but then costco do their own which is 3 ply and it is cheaper.
You will need huge storage for it though as you will buy about 60 rolls in a go
We buy a large barrel of kenco coffee, huge fairy washing up liquid (you have to decant it into a normal bottle) a wheel of brie (yes we share that!)
Your freezer has to be your best friend, like chicken breast you buy as a pack of 12 breasts.
We buy 2 loaves of bread (you have to buy it as a 2 pack but is lasts 6 days!) and we have granary, its £1.80 for the two and we were paying well over £1 per loaf in tesco.
You can walk away from stuff you may not need and then go back, there is no compulsory purchase!
For the first time we went we didn't actually buy much but we wrote down everything we thought that we would buy and then compared it to tesco where we usually shopped. The majority of stuff worked out cheaper. The meat is better quality, steak, tuna steaks are massive and we buy a whole half of a salmon cut it into portions and freeze.
No - they do not take credit cards so it is either cash, cheque (I think) or switch. Definitely cash and switch.
We are complete converts, they do lovely hot cooked chicken, they have taste samples of absolutely loads of stuff (the children love it) pancakes and maple syrup, chicken stir fry, they are always promoting the products.
I wont have a bad word said about it!