Quote Payment Option

Hi, I have looked through the community forum, can find a lot of request about it but now module or solution for it at this stage.

When I send I quote with a request for a deposit on it, and the client pay’s the deposit in, how can I add the payment for the quote to IP? as at this stage only invoices can have payments on it!

I only want to send an invoice out once all work is done. as if we send out on invoice beforehand we need to pay VAT on that also.

can someone please point me in the right direction. please