Peugeot 206 electics

About 2 weeks ago i got back to my car unlocked it as usual (remote central locking) put the key in the ignition went to start it and as i turned the key the 2 ignition lights turned off and i also noticed a faint clicking sound when i turned the key and both loghts went out and when i tried again nothing happened and still no light. I tried taking the key out and putting it back in but still no lights only lights for oil etc on other side. I got out of the car and locked it then unlocked it again tried it again and this time both lights came back on and it started and no problem, but the central dash which tells you the date, time etc had reset and gone back to french! aswell the stereo had reset and nothing was stored. Now this has been happening most days now for a couple of wks, when it happens i have to get out shut the door lock then unlock it and away it goes starting fine, but eveything reset.
But this morning I got back to my car unclocked it went to start it and it wouldn't, lights went out so got out locked and unlocked it got back in went to start it and nothing, got out tried it all again and still nothing. My hazard lights wouldn't work and all the dash lights had gone when i turned the ignition nothing..dead. after about half an hour of trying different things checking the battery, even seeing if the cigarette lighter would work, nothing, so was just about to call the AA, i put the key in and i heard a beep, i then turned the key all the lights came on and it started! now i've just driven it home and thats it. At first i thought i nd a new battery but it wouldn't have just started like that surely? or maybe something to do with my key fob and the cars imobiliser....if it has one actually! please help??

sorry its so long winded!