Sudden Knocking Noise

Hey guys,

Just got part way to work when i heard a knock noise when i applied the brake.
Sounds like it is coming from Front Drivers side but i feel it aswell if that makes sense?

It only happens when im driving forward if i put it in reverse and brake nothing happens.

Any input would be great!!!

prop shaft/UJ?

thanks for the input Jay will have a look after work im sure if it goes on the way back ill find out

have a wriggle underneath and check for play, nice day to do it!