Your going through the wars by the sound of it at the mo.
Sidelight:
Get a 12v test light and check there's a live getting to it at the bulb end. Make sure it's nothing silly like a dodgy terminal or earth, loose connection. If there is no live at the bulb when switching on, check the switch itself, see if there's a live there. Check for any breaks in the wiring.
Brake light:
A bit of glue should sort you out temporally for the lugs hopefully, and maybe some washers. If the worst comes to the worst and there's no way of attaching the light, then a bit of gaffa tape wrapped around and stuff the light in so it dont fall out to get you through the MOT. I'm not sure if LED's are a failure, but the built in LED indicators are! So just disconnect them at the flasher relay or somewhere like that. Or as you say stick the original back in.
Rear Indicators:
Have you got some spare original rears? If so that's a straight forward enough job. Hopefully the original wires are there still so it's just a case of plug and play. Unless they have been used as a feed to the led indicators in brake light. Either way should not be too big a job.
Handlebars:
Don't know, that needs looking at! I expect it's something to do with the stopper on the modded front end being taken off. You might need to get a piece of metal or bolt welded/glued on as a stopper.
Head Bearings:
Are you sure they don't just need tightening up a bit. If it's that bad/loose it could be linked to the problem with the bars hitting tank.
Get yourself some spare fuses and electrical wire. I'm sure your gonna have to run some wire somewhere. Indicators or something! And you might as well get yourself a selection of crimp on terminals. Saying that, as a bodge you could get by with a bit of electrical tape for the MOT's sake.
If I was you I would start with the silly thing's first, light's etc and then see what can be done about the bearings and the handlebars.
The bearing and handlebars might be a problem, but by the sounds of it you just need it all patched up to get you through the MOT. Then you can fix thing's more tidy/permanently on the workshop day.
Keep us informed to how it's going. If you need some help PM me, I'm not too busy next week. How are you set for tools, let us know if there's anything you need and I may be able to help.
(:-})