Thanks for the reply GJC web Design, really appreciate you taking the time to respond :-)
I have been dreading this for a while because it will be a lot of work to redesign my site but if it comes to it I will take the plunge and go for it
I have very basic PHP and html coding skills and understanding but just wondered if you know whether there is anything that I could look at doing to either stop the javascript errors in the first place or whether something can be done so that the add to cart functions differently under the edge browser?
I have upgraded to Firefox 40.0.2 on my Windows 7 PC and it is working in as much as I can add a product to the cart and checkout so I am a bit puzzled! - Unless Windows 10 version of Firefox is behaving differently, I wont get a chance to test under windows 10 until tomorrow
Cheers,
James