We recommend flying to Riga, Latvia's capital city. You can then use this as a base for exploying Latvia if you're coming out before or staying on afterwards. The venue is just over an hour's drive from Riga.
Airlines flying to Riga
Probably the easiest option is to book a flight with Ryanair. They run direct flights to Riga from London Stansted and East Midlands airports.
airBaltic fly from London Gatwick. So is a good option for those closer to London.
Also Wizz Air fly to Riga from London Luton.