Guess what I've done now!

I'm sure Halfords will have them, but they are one of the most ecpensive places to buy stuff these days. Any motorfactor will sell them. If you look in the fuse box on your car, I'd expect there'll be some spare fuses in there somewhere.

Glad you sorted it Rosie.

I was mixing up my threads .... https://www.caravanclub.co.uk/club-together/discussions/ask-the-expert/ask-the-expert-live/12v-wiring-issues/ 

Nooooo! Please don't tell me I've got to find more fuses . That means I have to find out how to open the bonnet

Your car's fuse box could be under their bonnet, inside the car or both .... just go to Halfords  

You could look up car fuses in the car manual to find where the little box is.   Most service/petrol stations will sell the fuses Halfords are pricey but convenient sometimes!

Always worthwhile carrying several spare fuses. I have had three blow in the last 11 years. 

1st one on previous van when one of the outside towing lights would not work when checking before leaving site. Car lights worked fine. I was surprised to find that it was one inside the caravan that had blown. Replaced it and all was fine.

2nd one when I plugged a 12 volt tyre pump into the 'van. Fuse blew and I replaced it, tried again and it blew. Replaced and checked to find that the socket under the TV had a higher rated fuse and I used that socket no problem. So used 2 spare fuses.

3rd one after the dealers workshop had done some work on the oven. Went away for Christmas break and the oven/hob igniter not working, No big deal but it also affected the fan for oven and grill. Couldn't do a leg of lamb in the oven with no fan to keep controls cool. Replaced fuse and next time I used the hob automatically pressed the igniter button despite having put a gas lighter to hand. After the second time I made the mistake I taped a bottle top over the button,  So used 3 spare fuses.

Moral of the story for me is carry plenty. 

With modern cars finding the two fuse boxes is one thing. Finding the particular fuse not always so easy. When my central locking packed up the only door that could be opened by key (not remote) was the drivers door. Could not open any passenger door from inside or out. Spoke to an auto electrician on the phone who suggested that (as I suspected and hoped) it was likely to be a 'tired' fuse that had blown. He also said that it would not be marked or listed as that one rarely is in his experience. He was right. I could find no info. Spent an hour or more on the web and finally found a post saying that on the 12 month old X-Trail the fuse was under the dashboard and top left. As I lay on my back under the dashboard and pulled that fuse I was so glad that he was right! 

Spare fuses not accessible as locked in boot! 

Just the two fuse/relay boxes Easy? There are fuses all over the place on my car and when I recently replaced my battery (under the driver's seat .... real PITA) I found some more.

Only two main fuse boxes that I know of. Not to say that there are not other Bs hidden away.