You have to know that Mildreds Soho is ALWAYS full. And no, you cannot book. However, you won’t have to wait very long, especially if you avoid getting there around noon. The downstairs room is quickly very noisy because the voices resonate in it, but you will get used to it quickly. After all, you are in London and the restaurants are often very noisy. There is also a room upstairs.
Mildreds dishes are only vegetarian or vegan, and everything is perfectly indicated. The staff is particularly efficient.
Our advice: have lunch around 11 a.m., the place should be a lot quieter.