What’s the right setup for Highlands & Islands shipping?

Highlands & Islands (Scottish Highlands, Hebrides, Orkney, Shetland, Northern Ireland, Channel Islands, Isle of Man) are a known Magento gotcha — carriers charge surcharges of £5–£25 that vanilla Magento doesn’t apply by default. We:

1. Add a postcode-prefix matrix (IV, KW, PA, PH, ZE, BT, GY, JE, IM ranges) to shipping_table_rate.
2. Wire ShipperHQ rules so only Royal Mail or specific premium carriers serve those postcodes — no DPD next-day promises that can’t be kept.
3. Apply surcharges in checkout with clear copy (“£X surcharge for Highlands & Islands”) so customers don’t complain post-purchase.
4. Optionally exclude express options for those regions to avoid late-delivery refunds.

We’ve shipped this for a Manchester homeware store + a Glasgow whisky retailer.