First you'll want to check if you need a visa to enter the UK.
- Nationals of the EU, Switzerland, and EEA countries will not need a visa, and are free to work and conduct business in the UK.
- Nationals from some designated countries such as USA may travel for tourist or business purposes under a visa exemption. The link above will detail what documents you need to provide in order to travel under a visa exemption.
- Other nationals will need a visa.
The rules for allowable business travel under a visa exemption are covered by the same rules as those travelling under a vistor visa. If you will be travelling under a visa-exemption and the conference is covering your costs in any way you should make sure to read the relevant section below.