2006 Vauxhall Corsa Emission light illuminated

Hi,

My car passed its MOT 2 weeks ago and passed but I queried the electrics as on one occasion recently the dashboard dials did not work (I only realised this when I was driving and when I stopped and re-started the dials were working fine) and the car has seemed to periodically struggle in the lower gears recently. The garage said the ampage was slightly low on the battery and they quoted a price for a new one. I explained that the battery was only 3 years old and was put in by them, so I asked what the reasons for this could be. They said it was probably just wear and tear but I told them the car doesn't really get that much use. I drive it around time and drive from Harrogate to London about twice a year (along with trips to the coast). They said that it probably just needed a good long drive. Last night was very cold and the car failed to start but with the help of my neighbour we managed to push start it. This morning I took it for a drive up the M1 and back home. This afternoon after I dropped my son off I noticed the emission light is now illuminated. I have read that this is a common design fault with Corsas in that the light comes when there isn't an underlying problem. Please can you advise? Many thanks.