BiFest is a one-day event celebrating bisexuality, for bisexuals and bi-friendly people. Originating in London, it has now spread to several other UK locations.
Wales has hosted a BiFest every year since 2010. It is likely that there will be one in May 2018 - watch the Bi Cymru page for updates.
London BiFest is back at the Kingston Quaker Centre, the venue that was so successful last year. The site at london.bifest.org has details.
Birmingham BiFest is an annual event that has usually runs in November.
Not a BiFest, but a similar event one-day event in Grasgow hosted by The Equality Network. This has run for the pas two years, and there will probably be one in 2018. Details at the BiTastic! site here.