I have a Volt from SI, and that got my sister interested in this as well, and emailed SI to ask if they shipped to the UK. They said they did, but she ultimately went with a Joye 510 from VapeEscape, because she couldn't wait an hour before I got home to talk about what kinds she would be well off getting, but I think she made a good choice.
Anyway, I don't know who, if anyone, has SI stuff in the UK - I live in the States, my sister is at Cambridge.
EDIT: You might also want to ask in the Smokeless Image forum in the Suppliers forums.