First time visitor to the U.K. Sat Nav Question...

2g will take forever and a day to feed Google Maps (or even Waze).

And won't work at all if you wind up in "Not-Spots" of which there are many in various parts off the country. It will depend on where you are going.

Downloaded Google maps will work offline - but it's not the full bells and whistles service that works when you're online.

Don't stress it's only the internet.

The most important thing to know about using a Sat-Nav in the UK is how the UK postcode system works.
Postcodes are alphanumeric, for example: W1A 1AA
Unlike in other countries, the postcode relates to about 5-10 houses, or for businesses, hotels etc. each has an individual postcode.
All you have to do is enter the postcode into the Sat Nav, you do not need to put in the full address.

Most places you will want to go will publish their postcode on their website or leaflets, for example:

Satellite Navigation:
If you have satellite navigation in your car our postcode is NE13 8BZ.

Thank you, that's what I was looking for. I can get a Nav unit from the rental place at a very nice premium.
I have offline maps downloaded, but never used them. I don't mind getting a little lost on the way either. :)

If you have an unlocked phone, you can get a local SIM card. They are fairly inexpensive.

You might also give map.me a try. It works just great in disconnected mode if you've downloaded all the maps beforehand. I've used it san-cellular connection on both IOS and Android devices.

However, I personally think a local pay-as-you-go SIM is the BEST option. I used O2 and was really happy with the service.

I and my wife drove in the UK (Wales) last summer. I disagree with most of the input. You are better off with a dedicated navigational app. We used Co-Pilot which ran on both our iPhones and our iPads. It did a good job of showing us round abouts and navigating us through the round abouts. All it does is navigation and does that very well. There are other dedicated navigational apps available. Some of the apps mentioned are good for walking or getting a lay of the land but do not route well when not connected to the Internet.
Be sure you know how to use the app before attempting to drive in the UK. Narrow roads, left handed driving, a stick shift, and a unfamiliar app are a difficult combination. Even with a good navigation app it is very helpful to have co-pilot/navigator to operate the app and watch for traffic signs and otherwise increase situational awareness in an unusual driving environment.

Co-Pilot looks pretty sweet. Especially with the roundabout help. I'll get that going! Thanks Again!