I have spoken with Les above and he has provided us with a quote and a turnaround time of a few days. As you are in the UK and I am in Spokane, Washington our time zones are a little off :) Please feel free to contact me via e-mail at firstname.lastname@example.org, with a subject line attention Sadie Prosser.
Please let me know how much you believe this would run us and how long it would take to accomplish this. I will need to be able to change the values from year to year and am very comfortable using MAMP PRO and phpMyAdmin.
As stated before I can create the tables as instructed to do so if that helps in cutting the cost by reducing the time you would have to spend on this.
Ideally, it would be great to have a customer enter their event date (or dated needed by) and then the shipping destination. So if someone wanted to place an order on monday and their event is on friday we would need to make sure that their package arrived no later than thursday. So if they decided to go UPS ground because they wanted to save $$ but didn't realize that it would take 6 days to their location, the code could include an if else statement to change the shipping to fedex 3day. Please let me know, thank you for your interest.