Going to use this all for example.

We just reached our release level and the account now shows 0.00 ...

But we had $24 over the release level at the end of the month, I presumed they would leave that $24 in and send just the release level funds.

Am I to understand if say your release is at $800 and you've got $854 at the end of the month, that they will send it all to you?

Does anyone know how long it takes for their cheque to reach the UK by mail?

yes, they will send it all to you. This is one of the reasons I like 2checkout. they do not hold any money in reserve.

sorry, can't help with the UK cheque question. I am in the US and it goes straight into my bank account.