Your best bet is to first get confirmation from the relevant import authority in China. I would suggest that you contact the UK Embassy in China as they will be able to get in touch with the relevant import authorities. Talking to your customer might also be useful, but it’s always better to get formal advice from the relevant authority.
Pending their confirmation, you’re very likely to need to contact two UK agencies: the Food and Environment Research Agency (Fera) and the Rural Payments Agency (RPA).
Fera provide a range of services to help UK businesses export plants, plant products (including grain and bulbs), fruit and vegetables, potatoes (including seed potatoes), seeds, soil or agricultural machinery to countries outside the European Community (EC). They provide phytosanitary certificates that certify that a product is free from harmful plant diseases. Here is a link to a summary of their services and here are their contact details:
Food and Environment Research Agency
Sand Hutton, York, YO41 1LZ
Tel: +44 (0) 1904 465645
The RPA can get you an export license and ‘Certificate of Free Sale’, if it is required by the import authority. Whether you need an export license will depend on your products Combined Nomenclature (CN) code (a means that the EU uses to classify goods) and the volume you’re exporting. You can find out your CN code by calling the Customs Classification Helpline on 01702 366 077. You can then arrange for an export license by contacting:
Rural Payments Agency
Trader Schemes, RPA Newcastle, Lancaster House, Newcastle upon Tyne, NE4 7YH
Exports of Food Products (CAP)
Tel. 0191 226 5046