Where can I buy an Ocarina from the UK?

Where is 'here'? The most obvious place to buy an ocarina in the UK is www.ocarina.co.uk. The reason postage & packing are high is that the ocarina has to be protected. You could just try going through every site that sells them, which would be tedious, but as you didn't say why it has to be from the UK (I umed that's where you are), it's difficult to advise you. Or, you could try re-posting in the Music forum and see if there are players who could help you.