In order to properly map the UK layout Qwerkywriter with you mac, you have to make sure your have a British PC layout added from your Keyboard control panel under the System Preference settings. This will ensure that you're Qwerkywriter is fully compatible and will properly give you access to keys like @ and " keys.
First goto the Keyboard Section on the MAC
Then Add British -PC
You should now see your proper layout.
Now select the British PC layout and you should be all set. Should you go back to another keyboard (why would you?) but if you did, you can switch back to the layout that matches your hardware Keyboard layout.