Add optional insurance cover to checkout

Hi,

I need to add an option for buyers to choose insurance cover for shipping.

There will be one price for overseas buyers and another for UK buyers.

I am using the Pro3 theme from marketpressthemes.com and also have the MP Custom Shipping Form plugin in place.

Not sure if my brain is slowing becoming non-functional, but I am having trouble getting these extra options into the checkout.

Has anybody else needed to do this and if so, are you able to offer some advice?

Thank you to anyone who can offer any advice.