Well iv blown down the fuel line and found that the nut was really loose! Probably answers the air bubbles coming through, and found the small filter in the carb and it was completly caked full of muk! Sorry for the incompetence, completly missed that! Cleaned it all out, took the carb apart again and cleaned it all through again. The bubbles have now stopped and it seems to run better, but like I said, it was/is intermittent so gona take it out Wednesday night and see how it goes! Im feeling quite confident!
Will let you all know how I get on.