Here are some links that may help on the subject of importing
(shipping, paperwork, tax, duty, etc):http://www.usembassy.org.uk/fas/import_procedures.htmhttp://www.businesslink.gov.uk/bdotg/action/layer?topicId=1073858802&tc=000KW020232027
You'll also need to check that your products are correct for UK sale
... you don't mention what products you're looking at but here arew some links that talk about various product types:http://www.rbkc.gov.uk/EnvironmentalServices/FoodHygieneandStandards/labelling.asphttp://www.wyrebc.gov.uk/Council_Services/Licensing_Services/Premises,_Person_and_Business_Licensing/Sex_Shops_Licensing/Frequently_Asked_Questions.asp
As both of those latter sites are run by Borough councils ... perhaps a phone call to your local Borough Council or a browse through their website would be a good way to research further. They can probably help you with market trader licenses
Running a business in general
- you may need to set up a partnership and keep separate books, or perhaps something else - I'm no great expert. Failure to do so could mean that the taxman would want to treat all the money you take on the stall as personal income. Then there's business insurance, employee's right, etc (even if you're the only employee). I've been searching and came across:http://www.startups.co.uk/YY57hnE.html
for example ... and I guess there's a lot more on that and other sites.