Long winded answer, but bare with:
If you can, log into your online bank and export the last 30 days into a CSV file.
Open that with Google Sheets or Excel.
Adjust the cells and columns and such so you can read the info.
There might be extra columns you don't need so get rid of them.
What you want is a table that has business paid, amount, when. So something like:
BT - £50 - 13/9
Tesco - £34.99 - 10/9
So on and so on.
Then in first empty.column go down each entry and type in 1 of the following letters:
U
I
O
You type 'I' next to an entry that's 'Income'
You type 'O' next to bills and Direct Debits ('O' standing for Outgoing)
And the hardest one that you'll need to be really honest about:
Type 'U' next to everything that was Unnecessary. So an entry might say Tesco - £2.87 - 7/9, think back, was that KitKat, can of coke and copy of Big Builders Monthly really a necessity? Nope, Mark it 'U'
Amazon - £3.79 - 1/9 think back, did you really need a wine bottle topper in the shape of a golden asparagus?
Be really harsh and honest.
Do that for every entry in your sheet. The letters are really close on the keyboard donor can be done in a few minutes.
Then, once you're done. You'll be left with a sortable table that you can show just your incomes, just your Bills and direct debits and standing orders etc. But also, all the small, unnecessary £2 here, £4 there, type outgoings too. Be sure to include any cash withdrawal in the 'U' column unless you can remember precisely what you took the money out for. (Include cash withdrawal as U because sometimes, for example, you'll draw 30 and pay someone £26, but have no idea where the £4 went)
Select all columns and apply filter. Then filter the UIO column to show just the 'U' entries.
Select all of the entries in the cash amount column and at the bottom it should give you a total of all the money you've spent unnecessarily in the last 30 days.
Some may not strictly be unnecessary, so you can filter those out.
But eventually you might be able to see where your cash is going.
I do this regularly and it's always a shock to see that these little unnecessary spends can total up to a few hundred over a month.
A pop to Tesco in the afternoon for a treat, sure it's only £2, but do it regularly and it mounts up. Cheap things off eBay or Amazon when you're browsing for nothing in particular, again, it's "Only" £5 but there's been 5 "Only £5" purchases in the last fortnight. So on and so on.
Money is pizza...
Sure some slices are huge, but if you nibble the toppings crusts, you'll still eat the whole pie eventually.