I need to take my car to France this weekend and my lights aren't working!!!

I can only get parking lights and full beam to come on - no dipped beam. I thought it was the switch stalk unit so switched it over with a second hand one I bought, but the problem is still there. I took apart the original switch to see what it looked like and it did look quite gunged up, so I cleaned the points and will try putting it back on just in case I was unlucky enough to buy another unit with exactly the same problem (although I am thinking this will be unlikely).

I have checked the fuses to the right of the dash on the inside of the driver's door and they are all okay (I assume this is the right place?).

I have tried new bulbs but no joy. I think it would have been strange for them both to go at once, but I checked anyway.

I spoke to a garage today and they mentioned a "relay" which could be the problem. Can anyone expand on where thi sis located and whether it is likely to be the problem?

I did discover when buying new bulbs that they are actually Xenon headlights which I think where an extra when the car was new. Could this make a difference to what the likely problem might be?

Any help very much appreciated!!!