Whilst researching historic vehicle registration I discovered there is now a free MOT reminder service you can sign up to send you a text or e mail a month before your MOT runs out The old service that cost a pound was discontinued but this is seems to be a new free service https://www.gov.uk/mot-reminder
I just use Google Calendar and set an annual reminder. After forgetting one year it was worrying so if there is a simple process I'd recommend anything that helps.