Why is lumic in a wheelchair throne, he’s got a metal body?

I'm not proud, but I laughed. I suppose it's supposed to be a throne, but the optics are awful.

I read up on the wiki later and realised they were meant to be in a gay relationship.

I totally forgot about that. I think Andrew Hayden-Smith sells it pretty well, and Noel Clarke absolutely doesn't.

At one point lumic “declares independence” - this dialogue makes no sense

I think he's referring to London, which I guess makes a kind of sense given the appearance of the PM in the previous episode, but yeah that line is a whole lot of nothing.