Hi,
You have to use a zone "restriction" on your payment plugins so you will have payment plugins for UK and payment plugin for the rest of the world.
Using a manual payment method like "collect on delivery"/"check"/"bank transfer" could allow you to create a "buy over the phone" method.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.