Peugeot 306 M reg, Immobiliser issue?

Can anyone help, the problem has just started a couple of days ago, i got in my car turned the ignition on put the code 1111 in tried starting the car (as the normal process) and nothing happened apart from the alarm going off which went quiet as soon as i turned the ignition off, the strange thing is that when i put the key in the car again the immobliser led was green and i could bump start the car. now i thought this was an flat battery but when i stuck an charger on the bettery it showed 75% charge, (i must note that when i connected the charger to the battery the battery was connected to the car still). last night the car failed to start after work, bumped it again drove it home, tried turning it off an on again as soon as i got home nothing, as if the immobliser had cut off the starting motor, gave it 20 mins roughly, tried it agian started!! and continued to do so the rest of the evening, this monring, started first time but when i got on the ferry (i travel across a ferry to get to work) turned the car off on the ferry tried again when we landed nothing...had to bump it to get to work.

please please if anyone can think of anything i can try or knows what the problem is and what it would take to fix it please reply.

thanks