If you have Excel, you can download a spreadsheet that contains the fares from all the countries and allows you to sort them from here. If you do not, you can view the rules and fares online here.

I suggest you make the actual booking through your local BA office and then give the BA CAI office the record locator so they can submit the itinerary to their rate desk and handle the ticketing. BA CAI will probably respond to FAXes. Their FAX number is +20-2-5747674