Just putting this lot here as a reference for some advice and meal plans.

Although I’m largely omnivorous, I’m currently tending towards being pescatarian and/or a bad vegetarian; going vegan is a step too far for me at the moment, although we’ve just bought some vegan cookbooks, so you never know.

https://www.bbcgoodfood.com/howto/guide/vegetarian-marathon-meal-plan

https://www.livestrong.com/article/444757-vegetarian-diet-plan-for-runners/

https://vegnews.com/2015/7/the-best-vegan-diet-tips-for-long-distance-running