It really depends on the week... during school holidays it can be easily £40+ It depends on what you include in the kitty amount... for example if you pay for annual membership of somewhere, do you pay that up front and then deduct that on a weekly basis from the kitty? We have private health club membership, Legoland pass, National Trust pass - they cost money and are usually an upfront payment.
Even in school term time we have miscellaneous costs - had to buy a bottle of wine this week for a school raffle donation. Even a cheap bottle is not that cheap, a little under £5. Then you have school cake sales and other such PTA fundraising.
So it really can vary and will vary depending on the age of the children. In my case, long gone are the days when we could go to a £2 toddler group.
If it is classes and picking up bread and milk £10-20 a week should be enough.
I spend anywhere between £200 and £400. All classes are prepaid so it is for - diesel, dry cleaning, shoes, clothes, presents for parties (if there is nothing suitable in the regift box!) food shopping (I do an ocado shop to come on Monday lunch time but we usually need other stuff during the week and it soon adds up!) parking (not often, we walk most places) farms/zoo/soft play (also not often) lunch out and coffee occasionally, craft supplies (must buy stuff for Father's Day!) postage if I take parcels to the post office.
I keep all receipts, even though my MB says I don't need to. And I usually run things past her if it is over £15-20, like shoes or a raincoat type thing. Although on Thursday I pointed her in the direction of the Hatley website to look at raincoats (charge wanted a shark one!) and she managed to spend £90!!
As others have said, it really depends on the wk and what you're expected to spend it on. This wk I've spent over £200 with vet bill, dry cleaning, breakfast and dinner out (once, and as a special treat at mums suggestion). Nice weather so we had ice creams after school, plus the usual milk, veg, etc. I can go some wks with spending £20. I always suggest a float of £40 a wk. Summer holidays are another thing altogether.
I spend Â£20-30 a week which includes food for the children's meals, milk/bread top up, playgroup. at the beginning of term there is a Â£40 charge for a class we go to which is paid for in advance for the term.
im given Â£100 cash every week in a small purse, never have spent it all.