Entry/visa requirements for the UK can be checked on https://www.gov.uk/uk-border-control. The most suitable scheme is the standard visa https://www.gov.uk/standard-visitor, under "Visit on business". Please do not select "Visit as an academic".
If you require an invitation letter for a visa application please contact yanyan.gao [at] ed.ac.uk (Yanyan Gao (chair of LOC)) and provide the following information in the email.
- Title (e.g. Dr, Prof., Mr, Ms.. etc)
- Full name
- Contact address