If you go down the Garmin/TomTom route, I recommend Tyre for route making. it is like a more advanced ITN converter. I use a Garmin 590, it's overpriced and has a steep learning curve IMO. I also have Sygic on my phone, using the same method as @Tonik. It is simple and works great. If you have an old android laying around, you can make it work. All the maps are downloaded to the phone so it is an offline system.