Fujian 35mm f/1.7

You're going to need a mirrorless camera to use that lens for anything other than macro, and it's not designed or corrected for macro.

The EOS M cameras are all mirrorless APSC. Mpb.com have 20+ Canon brand EF - EOS M mount adapters at prices from £69 - £83, it's worth making sure yours comes with the detachable tripod foot. They have a white 18Mpx EOS M10 in good condition for £134, but if you can stretch for it I would say go for one of their 24Mpx M100 cameras in excellent condition for £209 - £219. Better sensor, better AF, slightly more refined. I don't use my M10 nearly as much since I bought the M100.  Both have weak pop-up flashes that you can actually bounce in a tiny room, neither will take more powerful flashguns like your 5D II.  The flippy screen of those models is well worth having and there's an app that lets you control the cameras remotely from your phone.

I sometimes see the original M going for £150 - £200 complete with mount adapter.  It's basically a mirrorless 650D but, apart from the hotshoe, the M100 and M10 are more versatile and better vfm.  They might be a little cheaper on ebay, but that 6 month guarantee must be worth something.

Mpb.com also sell EF mount extension tubes from about £50 up. I don't know how close you need to go, but as a rough rule, with the lens focussed at infinity, the magnification is extension divided by the focal length, e.g. a 25mm tube will give you half life size with a 50mm (more than that at the other end of the focussing scale) or a 12mm tube will give (12/50) = 0.24x. You do need to stop down a lot as very little will actually be in focus.

Neither the mount adapter nor the sensor size alter the focal length of a lens, but a 50mm lens on your 5D II will have the same angle of view as a 31mm lens on a Canon APS-C sensor. Put the other way around, a 50mm or a 35mm lens on a Canon APS-C sensor will have the same field of view as an 80mm or a 56mm lens on your 5D II.