Don't. Get a garage to do it; make sure they've done it before. You need to buy the bulb from the dealer anyway as it's a special. Then you need to get the instrument panel out, to do this you need to remove the dash. See the related link for a video showing how to do it on a Zafira.
My advice; unless you have a good tool kit you should basically plan to spend all weekend on it. I would also recommend you find out the opening times of your local auto spares and tools shop in case you need to buy drive adapters for your screwdriver half way through.
10w40 semi-synthetic.
Both are 1.3.4.2.
In the Vauxhall Meriva 1.7 CDTi (2004 model), the cooling fan relay is typically located in the engine compartment fuse box. You can find the fuse box near the battery on the driver's side of the engine bay. Consult the owner's manual for the exact location and diagram of the relays for precise identification.
Stop try to avoid getting caught cheating
To reset the oil change light, hold down the odometer and clock buttons for a few seconds. (with the ignition turned on).
Push the odometer trip reset till you get to "oil" then press and hold down till it reads "100"
On the back.
Whatever your odometer reads
Have recently just had mine done on a 52 vectra at 65,000 but l think this was a little late vauxhall recommend 40,000 but you have to renew all tensioners and waterpump, comes as a kit, costs me £200 to have this done at my local garage.
its to the right of the steering wheel
Yes.
If you know where to change the odometer/tripmeter display... Instead of pushing that control, turn it counter-/clockwise to dim/brighten the dash lights.