A very useful guide which I carefully followed to a successful battery change. I didn't remove the screen cables as that looked very fiddly. Instead I opened the screen to 90 degrees and used 2 rubber bands to secure it to the original phone box with a piece of foam between. That was a very steady way to ensure I didn't damage the cables.
I also broke the sticky strips almost immediately so had to prise battery out. it bent a little but came out leaving the strips behind. this has the advantage of having the strips remaining to fix the new battery.
I got the battery and fitting kit from ifixit. the blue plastic levers that were included were not up to the job as the blade just bent when any pressure was applied. carefully using my own screwdrivers completed the task.