Renault Clio Noise when full lock left hand lock is on?

Hi folks

My son has an M plate Renault Clio in great condition. He is a poor student (haha) and has a problem with the car. When you have a full left hand lock on the car there is a clicking and you can feel a knock through the steering wheel whenever you hear the click. Suspected the cv joint although the clicking noise isn't one I would normally associate with the cv joint, neither is the knock through the steering wheel. Checked everything and the only thing I can see is that at the gearbox end of the left hand driveshaft there is an oil leak at the end of the boot on the driveshaft. The boot itself looks okay but there is no other leak I can find so the oil is coming out of the boot onto the driveshaft.

2 questions a) could anything else be causing the noise and the knocking through the steering wheel. b) if the fault is at the gearbox end of the driveshaft is it a job for a good DIY'r