I definitely concur with the advice to book a special meal - I wouldn't do this in Club, but always do in First. While two of the starter options are usually veggie (soup and another), there's rarely a veggie option in the main courses, although there's generally also a veggie pasta dish on the bistro menu (if you're not flying the A380, which doesn't have this option).

However, only a certain number of each option may be loaded and the veggie options could run out before your order is taken (unlikely-ish), which would leave you with nothing you can eat. So unless you have a smaller appetite or eat in advance, a special meal is safer!

I was less than impressed with my recent AVML experience, so don't expect anything special from your special meal!