Head down outfall lane and park at the bottom. Cast onto the gravel Spit. Or fish by the Lighthouse.

 

The gravel spit (Black Pipe) - 

https://maps.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=st+brides+wentlooge&sll=53.800651,-4.064941&sspn=18.723967,57.084961&ie=UTF8&hq=&hnear=Saint+Brides+Wentlooge,+Newport,+Gwent,+United+Kingdom&ll=51.523134,-3.021691&spn=0.0024,0.009012&t=h&z=18

Or park at the Lighthouse Inn  and fish over the bank. -

http://maps.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=st+brides+wentlooge&sll=53.800651,-4.064941&sspn=18.723967,57.084961&ie=UTF8&hq=&hnear=Saint+Brides+Wentlooge,+Newport,+Gwent,+United+Kingdom&ll=51.529004,-3.01014&spn=0.0006,0.002253&t=h&z=20