Just a few ideas here WWW that I do to save money:
V21 for internet usage - £10 a month to access the Net whenever you like. No strings.
Someone has mentioned charity shops, Scope, Barnardo's and Oxfam are good, dd has loads of Next and Gap clothes that cost a couple of quid.
Get your telephone connection changed to someone like Glow Telecom - we've never had such cheap telephone calls!
DON'T buy from the internet, most goods can be bought cheaper from the high street, although it does mean a bit of shopping around.
Sign up for a part time college course, that way you can get an NUS card which gets you discounts from shops such as TopShop and you get discounted entry into loads of attractions too!
Cut your own kids hair, no-one ever notices and it saves you around £5 each time.
Have a bath with your kids.
Don't use credit cards. That way you only buy within your means, you don't get any nasty bills or interest charges and you know exactly how much you are spending at any one time. Besides, I don't see how anyone can use a credit card now there's Switch.
Don't get kids meals in restaurants for toddlers. There are always leftovers for them to tuck into, and they can never polish off a kids meal anyway!
Make a resolution this year to try to grow your own veg. You don't need a big garden, just a bit of preparation. Potatoes are easiest, as are onions, just plant them a few weeks apart for a steady crop. And grow herbs on your windowsill, so you'll be middle class as well as better in pocket!
HTH!