Comments below
However I currently pay almost £900 in mortgage a month Has this increased for the new higher rates or is this something else you need to cope with?
council tax £120 - I assume that this is with single person discount?
electricity and gas £230 - you could possibly reduce this by being careful, depending on the size of your house
phone £17 - you could half this
car inc £65 - make sure you shop around
petrol £100
food £300-400 - are you sure this is what you spend? Is this all food, eg takeaways, lunches, coffees etc
cat food, vet etc. £100 - sounds like a lot, how many cats?
kids afterschool activities £95
water £50 - metered or rates? Might it be cheaper on a meter?
tv licence £14 - do you actually need this? If you don't watch live TV or BBC iplayer, you don't need it.
life insurance £73 - this sounds like quite a lot, but I assume that it's to provide for DC if something happens to you.
kids ISA £50 - might have to reduce this, if things are really tight
internet £26 - probably can't reduce this by much
The above comes to around £2240, which leaves nearly £900 unaccounted for. I know you say what some of this goes on, but definitely worth going through all your accounts to look if there's any areas where spending can be reduced.
For days out, can you get annual passes or memberships on rotation, eg National Trust one year, English Heritage the next, depending on what's available nearby so you can have days out without huge cost (obviously take a picnic, food at attractions is usually expensive, poor quality and at the end of a long queue, so worth avoiding for more than financial reasons).