@pecanmix
£150 doesn't seem like much. Do you get by on that ok?
I suppose it depends what is affordable for the family.
If we're talking about money that is available for adults to spend on non essentials, it's the lowest priority and you just have to share what is left after you've paid all essential joint costs including annual and irregular essentials like insurance, car MOT and repairs etc, and put money aside for emergencies and irregular costs like holidays, Christmas etc.
Obviously adults will need a certain amount of clothes, but £150 is plenty to cover that and you can manage on far less if you need to, you just need to be mindful in what you buy. Some people won't even have this amount that is totally spare, and obviously others have far more.
Second what @Driftingblue says about making sure you don't fall into the trap of paying child or household related costs out of your spending money and also putting money into different accounts for different purposes. Maybe also have a 'household essentials spending account' for things like groceries, that is separate from the account that pays the direct debits?
OP, even if you aren't earning money, obviously you are contributing to the household by providing childcare etc, and you could also help stretch the budget by shopping around, cutting costs, and perhaps changing your attitude to money if you have a tendency to overspend? If you've bought lots of things you don't use, could you sell any of them?
Maybe have a look at Moneysavingexpert? Look at the weekly emails and see what tips you can pick up or explore the site further?