Is your fuel filler pipe perished and starting to crack? Just replaced mine.
How difficult is it? It looks a tricky operation and I hear the replacement part is expensive.
The pipe is quite expensive, £95 from memory (I bought mine from Graham at Melvyn Rutters).
Fitting the new pipe is relatively easy, as long as it is a warm day; but getting the old one off was a

It age hardens.
However, if the old one is cracked, you will smell petrol.
Also, when you fit the new one, make sure it does not have any kinks in it, or you will get the fuel blowing back when you fill the tank.