If you are doing this for the pleasure of doing it there is little financial risk, if you own premises (this could be an outbuilding). If you don't own premises then you will have to pay rent.
There will probable by an issues of Public Liability Insurance.
If you are thinking of a business then you really need a premises where there is footfall (lots of people), this need not be on a shopping street (high rent). There are many docks, harbours, and quays open to the public; and these attract visitors at the weekend.
You can get free advice from your local small business adviser. They will be able to tell you about what you need to with regards to registering a company, insurance, and other regulations. You should be able to track the small business adviser down if you chat to the job centre.
Hope this info can at least get you started.
Mark