What SIC codes do you have assigned to your limited company?
The two SIC codes I use for my limited company are:
47990 - Other retail sale, not in stores, stalls or markets
47910 - Retail sale via mail order, houses or via internet
You can search more SIC codes through the Companies House site: http://resources.companieshouse.gov.uk/sic/
Type in retail and choose the codes which work best for your requirements.
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