Thanks everyone for all your help so far, I feel this is going to be a slow process.
I have started to stroke her and reassure her when we see another dog and have noticed a very small change in her .
But I still cant break her fixation on looking for other dogs , the taps on the nose and shoulder and rear do nothing its like I never did it.

At the moment I use a choke chain but it does not make her stop pulling when she sees another dog , I will look into a half check ?

The problem I worst on the lead , for instance today she was barking at some cows so I thought go and meet them and let her off the lead ( with the muzzle on ) and she then proceeded to ignore them ?? Also when we see other dogs and the is not tethered she just runs up grumbling - bark and just has a sniff and runs back to me , then if I put her on the lead she kicks off ??