Sidelights are a PITA to do fyi Alex.
Best way I found was, for example when doing the drivers side headlight:
Turn the steering wheel/front wheels all the way to the left, remove wheel arch retaining screw and bolts from lower part, pull the wheel arch backwards (preferably with someone else helping to hold it back), then you should be able to see the back of the sidelight bulb position & it's wiring. Twist out fitting and remove the old bulb from the holder.
Replace with new LED bulb, then check polarity is correct & it works before doing reverse to refit everything back together.
Passenger side is the same process but just with the steering wheel/front wheels all the way to the right.