I wouldn't buy a tom tom, I've got the tom tome one XL the wide/bigger screen version.
Look into the cost of map updates, you can buy a complete sat nav for less than the cost of a tom tom latest map, and not all the current roads are on it, so need the update as map share doesn't deliver them.
I went to Papworth(Addenbrookes) for a heart trace and the new roads the bypass bit on the A428 around Cambourne were not even on it, must be at least 3 years old the route now.

tabetha