Planning helps. Have a list of everything you would buy presents for (birthdays, anniversaries, end of term teacher gifts etc) and buy them in advance.
Plan your meals in advance and bulk buy things like pasta.
If you get paid monthly, pay each month's expenditure - credit cards, storecards, insurance etc - on that day rather than waiting until it's due (or at least ensure know you've earmarked that money and won't touch it). Then you know how much you have to spend freely in the month on non-essentials and can do so without worry.
If you can, pay some bills annually rather than monthly. You don't save much but I think it helps with planning and "feeling" that your monthly bills are less. it's only recently I have been able to do this though so completely understand not everyone is able to do this. Also negotiate everything before renewing.
There are basic butter cake or sponge cake recipes that work out at less than a couple of quid - master those and meet friends for coffee at your house or theirs.
Make friends with your freezer - so much stuff can be frozen rather than wasted. Rummage through the reduced fridge in Tesco/Asda - most stuff can be frozen. Pick up odd bits of fish there and save them up to make a fish pie.
Shop ahead of season for clothes - I've already bought winter coats for the kids as they were being sold off dirt cheap a month ago.
Personally I think clothing from the likes of Asda/Primark is a false economy - one wash and it's out of shape. You can buy three packs of t-shirts from next that keep their shape even after tumble drying. Gap outlet is also a haven for bargain hunting - you can buy online if there isn't one near you. Last year I bought coats, hoodies, jeans, shorts, tshirts for my two kids and it come to less than 70 - I literally struggled to carry the bags I had so much stuff!
Groupon can be good for meals out and entry to visitor attractions.
If you pay childcare, ask your employer about childcare vouchers.
Sell stuff - music magpie, envirofone etc are good for this.
I've been there OP, I've struggled and even though I earn a comfortable amount now, I'm terrified of being back in that place of gut-wrenching terror when an unexpected expense crops up so I'm still as frugal as ever! Good luck.