@Rainbowshine
Another thing that you need to budget for (which you might have included in your food costs but it’s not clear) is cleaning equipment and cleaning products. A friend recently moved (split from partner) and suddenly realised how expensive it was to get basic kit like bucket and mop, dustpan and brush etc.
huh? Did she not clean when she was with her partner then? Why would the cost of every day items come as such a surprise? Was she also surprised at the cost of loo roll or milk? Besides which, those things are far from expensive...a basic bucket/dustpan and brush cost less than two quid each from somewhere like home bargains, mop a fiver, add some 99p disinfectant or 39p bleach and sorted

. If you'd said cleaning items like a hoover/iron etc which could be more expensive outlays it might have made more sense but those are weird examples!
OP - lots of people have already suggested monthly budgets and logging all spending, but don't just do this for a few months and assume you're sorted - e.g. electric and gas could more than double in the winter compared to summer. For lots of things it's cheaper to pay upfront for the year (car/home/contents insurance, road tax, public transport ticket) etc. but make sure you also
Use a 'cashback' website for all the bills and purchases you can and swap insurance, gas and electric, etc, every year - I usually spend say £120 on h&c ins for a year and get at least £30 back via cashback. Same with switching bank accounts for the best introductory offers every so often.
Swap introductory offers for things like hello fresh, simply cook, uber, etc between a group of friends and make use of free trials for, e.g. prime, spotify, etc.
If you've got a stable job and need to make a big purchase (e.g. a sofa) it actually works out cheaper because of inflation to pay for something on 0% credit instalments than upfront.
Get all the store cards you can, clubcard, nectar, boots advantage etc. Even if you don't use them often they can add up. Often they link to other things, e.g. I rarely shop in sainsburies but earn loads of nectar points from ebay. Save them on an app on your phone rather than carrying them all round with you.
For the winter, buy an electric blanket or small heater and sit in one room with them on and a hot water bottle so you are still warm but not spending ££££ heating rooms nobody is in. Leave the oven door open after you've cooked food to warm the kitchen for free.
Have fun!