I'd set up a proper budget sheet.
Have set amounts going to lots of different pots eg birthday, holidays, Xmas, long term saving short term emergency pot, children's savings plus pots for future dc expenses, schools trips, when they do more expenses nights away with school, lessons, clubs, clothes.
I'd even open sipps for the dc! Self invested private pensions so they can have money for theirs retirement going with all that beautiful compound interest to build up for them.
(stock and shares of course)
Once you have done all of that see what's left. What's your weekend, fun spending? Your hobbies... Petrol etc.
After all of that you have your true free money. Then you have to factor in, the unexpected.
So for me, that's a brilliant primary school, rated outstanding and that worked for one dc, is failing the other. If I could put her in private with smaller classes etc I would move her in a flash.
So bear in mind the unexpected.