Nationals of non-EEA countries may need a visa to enter the UK. You can check yourself at the UK government site. The processing time for a visa is typically less than 3 weeks.
Please contact Sue Geddes (firstname.lastname@example.org) if you will need a letter of invitation from us, either to apply for a visitor visa or to present at the airport when you enter the UK. Sue will happy to discuss what visa you will require or whether any existing visa you hold would be appropriate for this visit.