There are so many ways you can do this and people have written in depth articles about it, so I am just going to share a couple of the things that have really helped me. This one wasn't especially easy for me because I LOVE good quality food and ingredients, so I had to keep reminding myself that the pennies I saved here each week would turn into pounds for our trip! This helped me to become willing to make some sacrifices.
Shop in a cheaper supermarket for most of your groceries.We now shop in Tescos topsail island rentals for most things, although we do get a veg box elsewhere, and if it is a special occasion I will get a treat from Waitrose.
Set a budget before you go to the shop. Our total budget for food and household shopping each week is 50. This includes food, cleaning products, toiletries and pet food, it doesn't include our veg box which is an extra 10 and worth every penny (health is also important to me!). However when I actually visit the supermarket I aim to do my shopping with 30. This leaves 20 for any little extras we might need to pick up during the week. And if we don't spend it all, well happy days!
Put the actual cash that you intend to spend into your wallet, add up your groceries in your head as you pick them up in the store. Next ask the checkout girl to stop when the total reaches your allocated amount (just in case you miscalculated). This means you will NEVER spend more than you intend, and it is surprising how quickly you will learn to add up your groceries accurately.
Use a list. This means you will know exactly what you need to buy and won't end up buying lots of extra stuff that you don't really need!
Look out for discounts and deals in store and take advantage of BOGOFs (Buy One Get One Free) You can save A LOT of money this way, provided that you don't get distracted by the offers and end up spending money on things you don't need. For BOGOFs make sure that you don't buy perishable goods that will just go off. Instead go for tinned or dried goods or household products that you need (such as washing up liquid).
Use store rewards cards. We are currently collecting Tesco points which we have linked to our Avios account. Avios points can be exchanged for flights or ferry crossings. Most reward cards will help you save money off your groceries, and it all helps!
Doing all of these things has actually encouraged me to cook more, and now we hardly ever waste anything. EVERYTHING gets used. I have really got into this and I am enjoying it. I get a buzz from seeing that we use everything and feed ourselves well, whilst still sticking to budget. Did you know that our grandparents had healthier diets during the war than the average one of us has today!