Interested in Triathlon?
For adults (and soon junior as well) the participation programme is called GO TRI. This aims to make triathlon fun and inclusive to all: https://www.gotri.org/ Earlier this year British Triathlon ran some specific Novice Disability Training Days and may do some more in the future.
However, the general GO TRI events are designed to be accessible and the focus is around taking part rather than what time you take. So these might be suitable for people with Vision Impairment.
British Triathlon would recommend ones with off-road running and cycling. You and members of your group can sign up here: https://www.gotri.org/pulse/
Within triathlon, people with a visual impairment are supported by a guide for all the elements and use a tandem for the cycle section. Unfortunately, we are unable to provide tandems centrally, but these may be available locally. There are also duathlons which are running and swimming and so negate the need for a tandem.
In London and Yorkshire regions, there are lists of people who are available to guide, so I can put you in touch with these if applicable.
There are also a number of specific events for participants with a disability. Please see this link for further information: https://www.britishtriathlon.org/gb-teams/performance/paratriathlon/national-events While most of these have already taken place, it could give you some ideas of things to work towards next year.
For completeness, the official Paratriathlon rules can be found in this document (beginning on page 54): http://www.triathlon.org/uploads/docs/itusport_competition-rules_december20141.pdf
However in GO TRI and more local events the focus will be very much on ensuring everyone can take part and it being safe and enjoyable for them.