I know how frustrating late payments can be, but I do find many childminders' approach to thesubject utterly baffling and not at all businesslike.
If on-the-dot payment is critical, then insist on direct debit arrangements through a business bank account. There are also specialist services like Gocardless who can set this up, but I’ve no experience with any of these.
In the absence of a proper business account, then have a standing order set up for a certain amount and let them top up the balance by BACS/faster payment transfer. That way, you have the bulk of money in on time, to the point where you shouldn’t notice any true cash flow problems.
Above all, never invoice in arrears, and always take a month's non-refundable deposit up front. That way, you can at least cut your losses if you need to give notice to a serial bad payer.
There’s not much you can do about the inevitable time lag with childcare vouchers, which is more the fault of the our own retail banks than the voucher providers. It’s not really any different to the delay a shop experiences in getting real money when you or I pay by credit card.
I wouldn’t recommend a 'no pay, no play' policy. Yes, it can work. But it can also be like hitting the self-destruct button. I know some CMs who swore by this approach, only to find it utterly decimated their businesses. I guess it depends on circumstances, but it's definitely taking a sledgehammer to a nut and can be very damaging.
Similarly, be very careful with late payment fees. They are quite easy for a client to challenge if they decide to get legal over it. The percentage of permissible charge is so small as to be unworthwhile bothering with.