Neil,
Unfortunately this is not that easy - while you can create tables for delivery based on item (weight, handling time, perishability) the settings for location based variations are only available for the US, Australia and Japan.
https://support.google.com/merchants/answer/6324484?hl=en-GB
You can see here that 'location_group_name' is a supported sub-attribute...but, like I say, it is only supported for the US and Australia (and location_id for Japan as well). Without being able to show these location specific variations you are then given an unattractive option...but unfortunately I think this is the one you will need to take.
"Overestimate if you can’t provide an accurate delivery cost. Match or overestimate the cost users would pay. "
Hope that helps.
Richard
