Its easy to access, remove cover between boot and battery, a metal cover on driverside has 4 screws. remove these and you will find top of tank. Remove wires, unscrew large retaining ring (you may need to use drift and hammer..gentle.. to get it started) then reach into tank and and fish arround for the sender its a long tube like thing and will be on bottom of tank ujust follow the wires. It then clips to the metal bracket vertically.
Warning: Disconnect battery before opening tank as fumes will be strong, do not spend long periods in boot as the fumes will make you feel ill, take regular breaks.