For business or academic visits,you can apply for a Standard Visitor visa if you’re coming to the UK for certain business or academic activities.

You can visit the UK as a Standard Visitor for tourism, business, study (courses up to 6 months) and other permitted activities. You can usually stay in the UK for up to 6 months.

You must apply for a Standard Visitor visa online before you travel to the UK. A Standard Visitor visa costs £115 for up to 6 months. The earliest you can apply is 3 months before you travel.

Please visit this link for more visa information:  https://www.gov.uk/apply-to-come-to-the-uk

Please visit this link for applying visa: https://www.gov.uk/standard-visitor/apply-standard-visitor-visa