This is weird. When a guy comes here and asks for a road bike, people recommend road bikes. When it's a woman, they recommend hybrids. I'd like to believe this isn't sexism, but I had the same weird experience of going into bike shops and asking for "drop bar commuters" and at two shops they immediately steered me towards flat bars.
Anyway, you want a bike that can take a rack, and mudguards. Probably a more relaxed geometry, as you are not going to get your arse in the air much in a London commute, and you'll need your head up a lot.
Have a look at Giant Avails. Very happy with buying one a couple of years ago. I think the
Evans Fuji is highly regarded at the budget end, and search this forum for Triban (from
Decathlon) that gets rave reviews.
Definitely get the mudguards when you buy the bike, and make sure the shop fits them for you.