alright mate the dreaded mot lol
well to answer some of your questions
1. flashing oil light wont affect your mot (might wanna check your oil level though) and the oil pressure thing is on the top of the oil filter housing think its the back one brown top from memory.
2. abs light is a straight fail (best thing to do for mot is disconnect the light by removing the plastic surround where the light is on and taking the plug off the back

) should pass then
3. back box shouldnt fail because its rusty as long as theres no holes affecting emissions leaks etc anywhere on the exhaust also the mounting rubbers and brackets need to be intact .
4. check your tyres are above legal limit, check all seat belts work by gving them a tug should lock straight away, check you can open all doors from inside and outside (no broken handles etc), check sills arnt corroded or maybe looking at welding!

, brakes are working correctly obviously your abs might not be but shouldnt affect breaking to much mine has passed twice with no abs working ! i prefer no abs tbh i purposely disconnected mine! theres other checks you can do yourself but thats the main instant fails could make sure none of your springs arn't snapped by bouncing the car on every corner and see if it settles with about one bounch that will check your shock absorbers arnt shot hope this helps
