Changing a fluorescent light
If the light is flickering then it is most probably the starter that needs replacing. If the light is shimmering or very dim then it is most probably the fluorescent tube that needs replacing. Either way it is your responsibility to change these in your home.
To replace the starter
Turn off the light. Press in the starter, then turn it anti-clockwise (a quarter turn) and pull out. You can then take this to most electrical retailers to buy a replacement. Then simply replace following the same method but turn it clockwise to lock it in place.
To replace the tube
Turn off the light. Unclip the diffuser (if it has one) and then grip one end of the tube and push towards the other end which will release it from the connectors. Measure the tube and wattage to buy a replacement. Follow the same instructions to replace the tube.
Changing the bulb in a bathroom light
If you have an enclosed bathroom light which looks like this picture then you will needs a Phillips screw driver (crosshead) and a 2D light bulb which you will find in most electrical retailers.
To replace a bathroom light bulb
The casing has 3 screws holding it in place, unscrew all 3 and take off the casing. Remove the old 2D light bulb and replace with the new. Simply refix the casing by screwing back in all the screws.
IF the screws appear to be triangular in shape please ring the call centre on 0800 358 6025 who will tell you what to do next.