You’ll find tons of threads on the forum if you do a search; this is one of them:
Mallorca 312 training - Training - TrainerRoad
My self I did it in 2016. My nutrition tips are probably best ignored as I threw up dinner the night before then breakfast so did it on an empty stomach (on hindsight it was maybe a sign of what was to come 2 years later). I was fine for around 130miles but bonked big time after that until I was thankfully saved by a farmer giving out oranges. Its a great atmosphere though, enjoy 