[cassell]

Exactly as Robert has said for courtesy light switches, the wiring is behind the kick trim panel which is simply held by spring clips to the car body. Once removed with a decent trim tool you will then see the black earth wire which feeds down to the switch. Unscrew the switch from the A pillar and pull off the feed wire, as a tip, remove the fuse or disconnect the battery to prevent your interior light doing a merry dance if the connector touches the body (which it will!).

Door check straps need to be inserted into the leading door edge with the door removed. Sadly it doesn't open wide enough to insert them with the door in place.
However, a cheat procedure is to slightly bend/bow the new check strap so that it can be inserted into the open door edge and then re-straighten it to align it with the A pillar mounting point. It's fiddly and quite hard but can be done with some brute force and a couple of pairs of mole grips.