UK VAT Return and Service Periods

[posie10]

Hi a quick question on vat returns. We provide services to clients for our own licensing and support and the current licence period is the 1/7/13 - 30/9/13, because of the way a few of them pay we have to invoice them a few days earlier otherwise we'd have to wait another month, which means the invoice goes into the previous quarters VAT period 1/4/13 - 30/06/13, they are rather large invoices for us and the invoice wont be paid by the time the vat is due which is hard on our cashflow, can I adjust this invoice out of the VAT Return and pay it on the next quarter in which the services are being provided?

Thanks!