I did mine by unclipping the wheel arch trim, pulling back the liner and reaching my hand inside to remove the bulb. However that was only required as I don't have the access holes to release the light.
If you have the holes in your bumper under the fog light you can release the light unit and it will pull out from the front - allowing easy access to the bulb.
You can just get to the RHS one by squeezing your hand under the bottle. You have to remove a couple of screws/clips and persuade the under-tray down then you should just be able to get your hand in. IIRC the front portion of the arch trim has to be unclipped.