Many thanks for all the help, could not get the push button to unscrew and was afraid of breaking it so I cheated and took the cistern off the toilet,
cut off the the chewed bit of plastic thread filed it square, put on the new tap connector, put the cistern back onto the toilet connected all the push fitting 15mm pipe and it worked.
BUTT
when the cistern filled up the water just kept flowing down the pan, it was really starting to p**s me off. well it took a quite a bit of force I actually thought it had snapped but the ferrell around the push button did unscrew and the lid came off.
When I turned the water on and flushed the toilet the plastic piece that that does the same job as the old cock was jammed against the side and did not rise with the water (it must of happened when I was tightening the tap connector) it was just a matter of holding the nut with spanner and turning the shaft until it was free.
Now it all works like a dream again
Sorry if this explanation is a bit long but I hope this might help someone else in the future.
So once again thanks for all your advice, it was much appreciated.
Kenny Everet