Good with front-end (mainly React.js but also anything JavaScript), done a lot of back-end as well (Java Spring, Node, PHP) but i'm willing to pivot completely.
From what I've seen, working with a good software consultancy for a while is not bad since they will give you a lot of initial training in stuff like software project management and the latest continuous integration/unit testing/agile whatever, which seems to be highly valued.
Move to London, there's tons of places hiring for people with React experience and it shouldn't be hard to find somewhere paying £50k + if you've gone some years experience.
I'd recommend not moving to London. Three reasons. 1. brexit kerfuffle, 2. London is way too big commuting is a killer. 3. Even though you earn more, it doesn't make up for the living costs really.