Finally after about 4 years I have no more knocking noise at the front end!
Garage changed both ball joints and drop links but the knock was still there. They discovered a very slight play in the front nearside shock, when they took it off it virtually disintegrated, the weight of the car had somehow kept the shock together. However on that really hot day we had in July where my car read 41c my air con compressor died, so £900 later I now have a knock free car and have my AC back, but a huge credit card bill! Front wings and door lock micro switches are next on the list. The guy at the
garage is was very impressed with the car and was saying how rare they are now. If you have a Cupra TDI look after it as they are becoming increasingly rare!