It's rubbish isn't it.
We've saved the remainder so can 'top up' income as an when needed and then anything we don't use will go towards DC in childcare when I go back to work.
If useful, some other things I read up on re KIT days, holiday, and extra earnings (as I wasn't sure which I'd be getting until I got the letter from my employer due to finding out I was pregnant a bit after starting)
Your 10 KIT days are paid at a rate discussed with your employer. These can be interspersed with your mat leave. But, any 'work' counts as a full day.
If you had a 'side job before the 26 weeks before you were 15w pregnant and are on SMP, you can continue that if doesn't infringe your SMP job contract. (I coach sport which I'm hoping to go back to in September one morning a week to get dollar).
If on Mat allowance, your 10 KIT days are spread across both main and any side jobs.
If you've not done any other side-work beforehand, you can earn £1000 per year (income, not turnover) without having to declare it, which helps - but I don't think this can be via payroll. Ironing / babysitting / copywriting / etc...
I also think you can rent out driveways and spare rooms (possibly not ideal with a new baby) and get £7500 tax free per year too and this is disclosed as extra income. Or Airbnb if you go away?
Re getting stuff= second hand is a lifesaver for keeping costs down to boost savings you can redistribute for when they're here - I think we've spent maybe £1k so far, all in - clothes, pushchair, (new car seat), cot, carriers etc. Fb marketplace is ace - and friends that have done with kids are KEEN to get rid of stuff. Baby stuff is often not used very much at all, due to babies growing so quickly!
We've been stashing an allowance for baby from now too - we've been setting aside about £100 a month, so have a cushion for when baby arrives for extras n stuff. Now it's just part of our expenses, and will help towards stuff we need for baby, and groups etc...
some are more expensive than you think! (like swim lessons)