Flat rate scheme (FRS) VAT and cash based turnover method

[VectraMan]

You just do it. If you pay the VAT in the quarter it was invoiced, or the quarter it was paid doesn't matter much in the end, as long as you don't miss any or count any twice. So put on the VAT form the invoices that have been paid and pay them that much.

[garnet]

Hi all
just a quick question. I am in FRS for VAT. In Notice 733 section 9 it states one can use cash based turnover method and pay VAT only on the paid invoices.
In my case my first VAT period ended on 30 of April. My last invoice is issued on the 30th of April but hans't been paid yet.
If I want to pay VAT using CBT do I need to let the tax man know, or I just pay VAT now excluding the invoice from the 30 of April?
In the general CBT VAT (when one isn't in FRS) it says you dont need to let them know, just do it, but is it the same when in FRS?