Very easy m8. Make sure you put plenty of penetrating oil on the nuts that hold the tank straps to your car... lift your rear seat up and remove the plug to your pump and think theres a pipe to remove here too. Its a good idea to remove as much petrol as you can (you wont get all of it!) as it stings in your eyes! ...yep, thats what happened to me! Remove the clips that are along the seam of the tank holding the long tube and try to retain these for re-fitting, lower the tank and just undo things slowly and make sure you have somebody else under the car to help (i banged my head even with some help... hmm... wonder if they just let it drop?? Lol
It was an easy job and not very memorable to be honest