Your GPSr will work fine here in the UK. As for maps, they are slightly better
than Your US topo Maps. Check out this Cache Page Click on the Streetmap link and have a look.
As for the mapping software. it is fairly expensive.
Paper Maps cost approx £7.00. Sorry you'll have to do the sums
You don't say where you are visiting.
Pop in to the UK Forum. We are very friendly