SIC code stands for Standard Industrial Classification code. Companies and Limited liability partnerships are required to provide these codes for Companies House to describe the nature of their business activities. This information is then registered and used to compile a comprehensive database of the types of businesses that operate in the UK.
You will be required to state up to 4 SIC codes when you file your first annual return - there should be no need for you to provide any such code on your company formation application. If your business activities change at any time, you can update your SIC code(s) when you submit your next annual return at Companies House.
If you need information on SIC codes visit www.uksiccodes.com in particular you might find this page useful http://www.uksiccodes.com/sicfinder.html you can input a company name or company description and it will return possible SIC codes..