Stock up on non-perishables when they're on offer, then don't need to buy them when they're not.
Shop around, most stuff seems to be on a cycle of being on offer in the big supermarkets.
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Wilko is cheapest for cleaning materials. Also kids craft stuff. At this age I used to buy reams of printer paper rather than drawing pads - cheaper in long run and she could draw to her hearts content.
Bodycare is cheap for toiletries.
We don't use fabric conditioner as we're allergic it's certainly not a necessity.
Add layers of clothing, throws before considering turning heating on/up
Sign up to as many free loyalty schemes as possible- especially handy come Xmas.
Save if you can toward Xmas rather than risk getting in debt. At your dds age she doesn't need much and she'll still have fun.
Shop for dds clothes out of season - I'm not meaning fashion but eg winter coats are MUCH cheaper bought in spring/summer, swimsuits cost pennies in winter - as pp said but for the age she will be. I never paid full price for my dds winter coats until she was well into teens and it was harder to predict size.
Review all outgoings and reduce/eliminate where possible.
Check out local library for free/cheap toddler activities. Summer is relatively easy it's winter/rainy days you get stuck!
Do the food shop a day later each week that means (I think) one week over 8 you're not spending but you don't really notice.
Grab the free mag in the supermarket - there's often vouchers inside and it's a free magazine to read. They usually contain cheap recipes and give an indicator of what food is in season too.
I agree with Wittow's cash only tip I've done that when things really tight it's easier to keep an eye on spending then.
Join local Facebook pages - not just for freebies/cheap goods but that's where local cheap/free events that may have limited availability are often advertised/mentioned first.
I also cut my own hair. Long and straight so easy to do. Occasionally dye it too - there's sometimes dyes in the pound shop.
Torvi is right about local colleges too. Mine at end of summer term often advertises on FB page asking for models to let the students do specific techniques and because you essentially don't have a choice in the style or whatever they do it for free. One of my dds friends got ombré hair colour free this way!
Mila - I won a 4 day caravan holiday once.
Go sim only on your phone ASAP. I'm not a fan of gifgaf I'm with Tesco have been for years. Even as a sim only customer I accrued loyalty points I was able to use to upgrade my phone when my old one had absolutely had it. I'll be doing this when I'm done paying for my phone - sim only from Tesco starts at £6 a month.
Wifi - I'm with Plusnet around £20 a month and reliable.
IF you're in a cold/draughty property - hot water bottles (can be used when sitting on sofa as well as in bed), electric blankets, make draught excluders for doors out of old tights stuffed with scrap paper, old clothes/rags, hang long curtain at outside doors.
Some charity shops have specialist branches that sell larger items too. The last tv I bought was £20! Furniture is often in great condition and very cheap.
Finally - budget for a weekly small treat, sounds counter-intuitive but if you're too puritanical it will soon piss you off and you're more likely to have a "fuck it" moment and overspend. Better to plan ahead.