Some people on the left can come over as poncified know-alls, but speaking for myself, I feel Labour represents working class people better now than it has done in my lifetime. They could definitely do better, but I definitely feel they are looking out for me and people like me.
I don't know anybody, on the left or the right, who thinks that Brexit = sending people back. Though, to be honest, how much faith do you have in the Home Office, in the event of a no-deal Brexit? We have seen British citizens deported with Windrush due to not having their paperwork in order. There must be loads of people from the EU living here who aren't paying attention to the details of Brexit and the steps they might need to take to ensure they have the correct documentation. Could be a problems down the road, and you can see why some EU migrants have either left or decided against coming here, due to the uncertainty.
Now, it's far, far from the truth that everyone who voted Brexit is a racist. I'm surprised that even bears repeating. Same for Trump voters across the pond. BUT...it's pretty certain that all racists voted for Brexit (or Trump). And there was x amount of dog-whistling to such voters, case in point Farage and his poster with loads of brown people behind him. Reasonable people who voted leave wouldn't be moved by that poster, but racists would. And that was the point of it.