fuel pipe
 

I am cleaning my tank out next weekend and changing my fuel pipe to rubber hose , has anyone done this if so what size inner do I need I have a grand voyager

How about small bore copper pipe instead, at least it won't sag. A keen MOT tester might not like this idea as its not standard.

the bloke who does my MOT who has advised me on it mate , plus copper is a lot of trouble to bend into place etc

£3 go for it, but don't use copper for [long term] diesel. Any tester who tells you copper is unacceptable get the advice number and print it here. Best of luck.