what i did:
remove fuel rail gaurd
remove all four injector wiring plugs
wrap a rag/cloth around the fuel pipe connector, squeeze and pull to release (normally a good idea to look the other way aswell at this point)
undo the bolts holding the fuel rail to the inlet
try and apply even pressure to all four injectors, dont just yank it
mine was pretty stubborn to remove but keep at it and it will come off (the injectors are just a push fit) and remember the rail is plastic so dont go using anything to lever it off, otherwise you might damage it
when you have the rail removed, remove the metal clips holding the injector to the rail and pull the injector out, replace with a new injector (sometimes recommended to rub a bit of fuel around the rubber seal to help it go in without damaging) note aswell if you push the injector in all the way, you wont be able to get the clip back in, there is a groove that it slides down, so you need to get the injector in the right position, you will see what i mean when you do it
repeat for all 4 and then refit the to the inlet, ensuring that they are well pushed in
refit the the bolts
refit the fuel pipe
give it a try (ensuring there are no naked flames around

)