The details you submitted have been sent to the organisers and you should receive an invoice at the e-mail address specified on your booking form within 2-3 days. If you do not, please first check your Junk mailbox and, if it isn't there, let the organisers know so that we can look into it for you.
The invoice will contain details of what you have booked, with prices, and a total to be paid within 15 days of the invoice date. The invoice will be generated by PayPal but badged with the WES2016 logo. You have a range of ways to pay; PayPal, credit card, bank transfer or cheque (only cheques drawn on a UK bank will be accepted).
If you made your booking before the close of the Early Booking Deadline (24th June, midnight UK time) then your invoice will show the reduced rates even if the invoice is not issued until a day or two later.