Please ensure you have the correctly orientated battery for your car connections. Do a visual check before you commence this proceedure.
If I remember correctly all you need is a 10mm spanner/socket and some petroleum jelly.
Unlock the car, you do not want the alarm going off when you connect the new one!!
Disconnect the NEGATIVE lead first, using the 10mm spanner, and move the lead to one side to avoid sparking.
Disconnect the POSITIVE lead and move the lead to one side to avoid sparking.
Undo the battery hold down clamp and put the nut somewhere safe, in your pocket is not a bad place.
Disconnect the wired connection on the left hand side of the plastic collar that covers the battery. With a bit of jiggling this collar can be lifted off the battery. You can now lift out the old battery. At this point, check that the umbrella shaped hold down strap bolt has not come out of its slot. The plastic cover removal can move it from where it should be. Check it and tape or tie it up.. now. Replacing the plastic cover is even more likely to move it out of position!!
Carefully lift in your new battery to its position, (remembering to orientate it the correct way!)
Refit the plastic cover and re-attach the wired connection on the left side of the cover.
Re-attach the hold down strap and re-connect the battery terminals starting with the POSITIVE lead. Cover any exposed terminal parts with Petroleum Jelly to prevent corrosion.
Start the car!! Should take no more than 30 mins.
You will need to ‘resync’ the electric window operations as described on page 45 of the Owners Manual.