I wouldn't restrict benefits to two children as it will deepen child poverty.
I'd increase NMW to a living wage and then scrap Tax Credits for people in employment so that the government is saving money but not making anyone worse off.
Means test some pensioner benefits suh as bus passes and TV license and only pay the fuel allowance to those resident in the UK.
Have some NHS services share facilities. As an example, where I live there's a GP surgery that always has at least two spare rooms and a couple of miles away there's a MW clinic that only uses one room. Why can't they share one building? The MW has a day clinic at the GP surgery once a week anyway so it wouldn't be a complicated move.
I'd overhaul MP benefits, get rid of the subsidised bar, cap pay rises, and make them spend more time in their constituencies and less time in central London (obviously excluding London MPs) to save on costs. Encourage multiple occupancies instead of second homes, if three MPS are working in London why can't they share a three bed house instead of each having a house? My old employer sent some staff away to set up a new office, they were in a hotel for the first couple of weeks at £560 a week each (£80 a night, four members of staff) until HR realised they could rent a four bedroom multiple occupancy house for £90 per week per person and save a fortune. No reason why some MPs can't do the same.
Charge for missed hospital appointments. I worked in the NHS and the amount of people who don't turn up for appointments is ridiculous. Also charge for replacement or repair of medical equipment provided, for example we'd get people coming in who had deliberately removed their casts because they were bored or it was itchy or they were going out and didn't want a cast on, one patient removed his because he fancied a bath without having to cover it. They would then need an urgent appointment in the oncall clinic, they'd need to be x rayed again to check they hadn't done any further damage, and a new cast would need to be applied.
Take over the counter medications off prescription (except for people entitled to free prescriptions or those who have a prepayment card). So Calpol, E45, ibuprofen, Gaviscon, etc.