Lumia with WP8.1. Not sure what GPB prices are, however a Lumia 530 is A$39.50. Crikey in pounds that's a round of pints at your favourite...
HERE Drive is pretty good (compared to a TomTom standalone), however the killer is that maps can be downloaded, for any country, for free, in advance.
I know that wherever I'm travelling, I can select the country map, download before travel, and it just works.
(Edited to add - the higher end Lumias have Cortana, and all WP8.1s have text swipe which makes address entry quick)