Was out riding today and the metal cage around the lower jockey wheel on the rear mech went missing (snapped off)

I think it’s new rear mech time however I’ was considering loosing the front mech anyway and going to a 1 up front set up.

The bikes 2011 spesh camber elite. I have a new deore crankset on which I was thinking I could maybe just remove a couple of the rings.

If anyone could point me in the direction of mech cassettes etc that would be appreciated. And also is it possible to buy the cage thing for the mech as a temporary fix until I can get my new set up.

Hope this makes sense. Thanks in advance for the great advice on this forum.