[Solved] Shipping price outside of UK

On my shop, I want my shipping price to be £1.50 in the UK, and £3.50 anywhere outside of the UK. The shipping will be fulfilled manually, hence I am using the HikaShop manual shipping plugin.

I am trying to achieve this by using a shipping plugin restricted to the UK, and another restricted to anywhere outside the UK. In the restrictions section of the plugin, I cannot find a way to select all zones except the UK.

Is this the best approach to this?

That's indeed the correct approach. As you found out, you can't select multiple zones in shipping methods. What you need to do is to create a new shipping zone via the menu System>Zones and add all the countries except UK as a subzone of that zone and then use your new shipping zone in your shipping method so that it applies to all the countries except UK.