Mk 6 headlights come on, flattened battery, and now engine wont idle?

Hi,

I was alerted by a neighbour one night just before Xmas that I had left the headlights on my Fiesta. The problem is, I had not even been out in it that day with the lights on, and the car was locked with no key in the ignition?

I unlocked the car, and the headlight switch was off! I then started the engine and after testing all the light settings, I managed to get them to switch off. About midnight, the lights then come on again, but would intermittently switch on/off, to the point where the battery flattened.

My initial thought was perhaps a relay issue, so I removed the headlight relays to see if I could get one at Halfords (no luck), but then my brother in-law popped around to see if he could help. We attempted to jump start it, but now there is a problem where the car will only start if you give it plenty of revs and will no longer idle? We did plug the relays back in, but no difference.

I am not sure if this is relevant, but for some time now, I have had an intermittent problem with the ignition, that my local garage could not replicate, or diagnose (sods law). Basically, sometimes you turn the key, and the little LCD temp/petrol gauge screen goes blank for a while, and then the little black markers dance up and down?

If anyone can offer any advice, then I would be grateful, and thanks for your time.

The car is a petrol 53 plate Fiesta Zetec, and I believe a 1.4.