The Britons Voting Abroad website is part of a university research project on overseas voting run by Dr Sue Collard of the Politics Department at the University of Sussex. It is designed primarily for British citizens who live outside the UK and who have an interest in voting rights in UK elections. (https://www.britonsvotingabroad.co.uk/)
GOV.uk have information on how to register to vote at the following link:
Contact the local council in your last place of residence in the UK with any queries.