clio campus sport 1.2 06 struggling to start- intermittent

[sharpy1.2]

Hi guys.
I've got an 06 plate clio campus sport 1.2 and I'm having problems when starting it.
I can turn it over, electrics come on radio etc no problem but then it doesnt actually turn over and the engine wont start.
This problem is really intermittent though-I can have no problems for days on end but then it just refuses to start, leave it 10 minutes though and it starts first time.
My mate suggested that it may be a problem with the imobilser and the chip in the key not being recognised and told me to open and lock the car several times and put the key in and out of the keyhole then try again-this does seem to work but its litterally a case of clicking the unlock button 10-15 times.
I'm terrible with cars and technical stuff so I apologise if this is a daft thread or the answer is located elsewhere-any help or advice would be greatly appreciated, i dont want to go to the garage to spend £hundreds when it may be something as simple as replacing the key in the battery.
Thanks in advance guys!
James

 

[da rok]

Normaly a starting issue is down to the tdc sensor, its located above the flywheel, try giving the plug a clean if it still wont start it could well be the imobiliser... the keys do go a bit funny sometimes

 

[S-Fell-89]

Theres also 3 black relays in the fuse box near the battery with 3, 5 pin relays. One of which is the relay for the starter, water gets in and creates a bad connection on it. If they are green (i.e had water on them) take them out clean the terminals on the relay and the connection too.