I've driver all over the place with just a map book, no problem.  So many roundabouts these days, I'm thinking of getting a satnav.  There isn't much room for a screen in my Mk1 Ford Focus.  I read that an android can be wired in, presume it refers to a phone, on the right-hand side is a good place.   Is there a satnav that will fit my car, or should I consider an alternative?  I don't travel far, have several long trips planned this year, France and Wales.  Being able to concentrate on traffic, not having to look for turn-offs at roundabouts, would be good.  I'd appreciate any suggestions you offer.  Kind regards.

Take a look on eBay or Aliexpress to see some examples of Android based head units that should be a straight fit into your Focus. 
 

Or just Google it 👍

You can still go old school with standalone SatNavs. I've had Garmins guiding me about for over 20 years. Most now include lifetime map updates without all the hassle of 'built in' units...

Mine also doubles up as a reverse camera.

 

I added this to my MK1 focus maps well out of date but was fun to show people I had OEM navigation in a 2001 focus 🤣