here is how to drop to "emergency mode", also known as "I fancy a holiday this year and want to go somewhere nice"
Open all your kitchen cupboards, take a good look at what you have, work out what can go with what and plan that out (here is the kicker though, it might not be nice meals, but food is food, we are talking means to an end here.
Your new shopping list will be Pasta, and knorr (or similar) stir in cubes, cook pasta, throw in cube, hey its pasta time, but with xyz flavouring added, again, not particularly fun food, but you just watch how much cash you have. Don;t be afraid to go and hang out at your local tesco / asda / sainsburys (not listed lidl / aldi here for a reason that will become obvious), as at about 8pm (you'll need to work it out) its final discount time when they really marks stuff down, if it meat you can freeze it and it will keep, again look at the packets, see how it can be stored, do not pay attention to the "best before" etc as thats not relevent once you have it frozen.
Look for offers, obviously don't stock up on digestives etc because they are 5% off, I'm talking 2 for 1 or 3 for 2, decent offers that make sense (also ask your work if they can sort you out a costco card if you got one near, as long as you have space there are some serious savings to be made by bulk buying)
Food is probably your number 1 expense after keeping a roof over your head, but its one of the easiest to push down the list..
Also got sky / virgin and not on the basic package, call them up, tell them you are thinking of leaving, they will usually offer a decent discount on your bills to help you out, contract mobile package and out of the initial contract, but its just rolling, that can be dropped as well (reduced mine from 40/mo to 10/mo (I need a large data allowance for my job, but found ways around that))