If you want to do business in the UK, you should apply to come here as a business visitor (or as a child visitor if you are under 18). This includes academic visitors, and doctors undertaking clinical attachments or the PLAB test.
If you want to come to the UK as a Tier 1 (Entrepreneur), and you need to spend time here first in order to hold discussions and secure funding, you can apply for a visa as a prospective entrepreneur.
If you want to come to the UK as a visitor to do short-term, fee-paid activity you can apply for a visa as a permitted paid engagement visitor.
Link | Visas Immigration