I presume the OP is referring to GPS software for the iPad. Whilst I have no experience with other GPS software available for iDevices, I am quite pleased with the TomTom app for Europe (which includes the UK, whoopee!).
It's a bit pricey for some tastes but one as long as one uses the same Apple ID it can be used on iPhone, iPod and iPad. Personally, I use the it on the iPhone for walking routes (and occasionally in hire cars, since my car has an OEM unit). With a suitable vehicle mount, the iPad would probably be quite satisfactory in a vehicle.