The shipping costs should be shown on the relevant website.
Import taxes and charges are calculated as follows:
1. Excise Duty = Zero (because alcohol and tobacco aren't involved).
2. Customs Duty (at the 'jewellery' rate) = 2.5% of the cost of the watch BUT it's waived if the total comes to less than £9 (i.e. if the watch costs less than the equivalent of £360).
3. Import VAT = 20% of the TOTAL of the cost of the item + the cost of shipping + the Customs Duty (if any). It's only waived if the cost of the item is less than the equivalent of £15.
4. Royal Mail inspection Fee = £8 (which is only waived if all of the above fees are zero).
So, for example, a watch costing the equivalent of £90 + £10 shipping would attract charges as follows:
Excise Duty = £0
Customs Duty = 2.5% of £90 but that comes to less than £9, so it's waived.
Import VAT = 20% of (£90 + £10 + £0) = £20
Royal Mail fee = £8
TOTAL = £28.