2005 Renault Clio 1.2 16v Wont Start

Hi all, i've have my Clio for about 4 months now, since i've owned it it's always done this thing where it will idle really badly (only for a few minutes) after starting it if i just leave it parked. If i start the car and drive it off straight away, it will lose and regain power about 3-4 times as im driving along, whilst i'm just holding the accelerator down consistently. (I'm saying this as i hope this'll help figure out what my current problem is).

But about a month ago the engine pretty much started deciding itself when it would and wouldn't start up, when this was happening all the lights would work fine and I would hear the noise as if it's turning over but just wouldn't start. We ended up cleaning the Crankshaft sensor and it started first time perfectly ever since then.. then suddenly 2 days ago it's decided not to start and all of a sudden the Electric Fault light has come on, this time when i try to start it, it doesn't turn over, just nothing. (But all lights and dashboard lights still work).

Now i'm thinking it cant be the battery because i've had that changed within the last 4 months..? I've also changed the spark plugs aswell incase that helps determine what it could be.

So i'm just wondering if you all had any suggestions about what it could be/what it's most likely to be? Thank you!