Got back in car went to start it battery was really labouring

Hi im in th UK my car is honda accord 1.8 vtec w reg 2000 checked my oil at work yesterday seemed a bit low just at bottom line on dipstick so coming home last night popped into get oil went to top it up it was a bit dark outside so left the lights on so I could see dipstick level, topped the oil up waited 5 mins checked it again, it needed a bit more done that waited a bit checked it seemed good just under top line on dipstick got back in car went to start it battery was really labouring went to start it again battery seemed dead, managed to give it a little push jumped in managed to bump it and got home, when I got home I tried to start it just to see if it would, it did. Went out to the car this morning put the key in turned it just made click click click clicking noise never cranked then went dead, I figured that as I only drove about a mile after bump starting it the night before it probably didnt get a good charge so just left it and went to work, got my friend to give me a start with jump leads tonight but nothing just clicking the green eye on the battery looked healthy so we push started it great off it went he followed me just in case, it was fine parked up again went to start it again just constant clicking no cranking tried it again and it sort of cranked with the bonnet up I could see the wheel with the belt on it turning a bit maybe a quarter turn everytime I turned the key got out scratched head sucked air in through teeth checked the oil as all was fine before topping up oil, oil level is a bit above the top line on dipstick about 2 - 4mm above certainly more than should be so tomorrow ill drain some off but why wont it start?