For me personally YANBU, cause we've been here and I know how rubbish it is. But there are things you can do. DH was made redundant last year and the new role he was offered meant a significant pay decrease and I was out of work, so days out were the first things to go. Remember that your kids only know about what is normal for them. Do a little bit of research on your local area, if there is any woodland, beaches, coastal paths or bridlepaths etc you could plan a walk through. A walk with a picnic or even just a picnic in the park.
Might not be ideal depending on your area but we were given National Trust membership for Christmas. I thought that we would never use it but we really do and have discovered places that we would never have been able to afford or would have considered otherwise. They're often really geared towards children and families. Any other days out we plan and budget for, or check for vouchers - our local rag is good for free child entry vouchers to local attractions around school holidays.
Saving money things (without wanting to patronise, cause people are full of good advice when you say you're struggling for money and less so when they realise that no, actually, you're not spending money on fags, booze and designer trainers, you really are that skint) check you have a water meter fitted, check energy tariff, switch to Aldi/Lidl, drop down any Sky/mobile tariffs if you can, ebay/selling page bits and pieces you aren't using at home.