Just heads up for anyone sending mail via Royal Mail. Not all their codes are IOSS approved. The following codes are approved and these are the ones we will be using. They are country prices.
MTK, MTO, MTG, MP7, MP9 and MTE. There may be more approved codes available but we only use those listed.
I would suggest calling Royal Mail to double check that these codes are on your account and if they are not get them added by the Business Team. If we do not use IOSS approved codes then we will run into issues with deliveries.