Dropshipping jewellery from China to UK

Hi all,
I have a couple of questions about importing jewellery to the UK from China and hope someone here can help.
If I were to order goods on behalf of a UK customer from a supplier based in China, who would be liable for tax and duty - me (my company) or the customer?
If the product in question cost me less than £15 to buy from the supplier in China, am I right in thinking it will not be taxed and no import duties will be due?
Finally, if I was to buy in bulk from the supplier in China, where can find the tariff for the different bands?
Thank you all for your help!