Following visit to the dealer yesterday they said the wheel shudder and pulling to the left is down to both front brake discs warping and distorting.
They have ordered new discs and pads but said they have no idea what caused it and have sent all info, diognostics and photos back to Citroen to investigate.
They said the discs would have eventually cracked and broken up - I've only done 9,000 miles!!!!
Might be worth anyone with car veering to the left and asking them to look into. I went to Arbury Citroen in Nuneaton so might be worth your dealer discussing with them.