Entering The UK As A Visitor

Can I come into the UK as a visitor and work or carry out business?

No this is not possible as working in the UK is a prohibited activity for anyone who is a "visitor" under the UK's Immigration Rules.

A "visitor" in this context is a non-UK national who has entered the UK either under a Standard Visitor visa, or visa-free because their nationality (for example, nationals of the US, Singapore, Hong Kong and European countries) grants them this entitlement, for a stay of up to six months. A visitor cannot undertake prohibited work in the UK, which includes (among other things) being employed here, carrying out work for an organisation or business in the UK and providing goods and services. There are however certain general business activities that a visitor is permitted to carry out including attending meetings and conferences, negotiating and signing deals and contracts and gathering information for their overseas employment.