My wife and I moved from the US to London back in July for the sake of adventure and it has been great. In fact, I'm answering this from Sorrento next to my wife who has already fallen asleep from a day hiking around Pompeii. I highly recommend London as a city both to travel from and to explore in its is right.

I'd be happy to hop on a video chat to give you more in-depth advice, but the short answer to your question is that yes, there are a number of companies tho are hiring and willing to sponsor visas. GoCardless, the company I work for does and the engineering team there is pretty great.

There are also a couple recruiters I know who are ethical, knowledgeable, and communicative.

As far as your specific background, am I correct in thinking that you doing network/telecom programming right now and you are looking to do more web/mobile?