To the OP – if you want to go for a low-tech proposal you might want to consider this set up:
1. Get a “tracca” nano GPS / mobile tracker for dogs- they are £100 with their current Facebook discount code:
http://www.traccauk.com/tracca-dog/
2. Get a sim from http://www.anywheresim.com . This roams across all UK networks so unless you’re in a cave there’s a good chance it will get a signal from one of the networks. A 1 year sim with texts and data is £60 – the tracking device uses a tiny amount of data and will only text if it’s called.
Pop the tracker in a freezer bag and put it your back pocket / back of your helmet / in your camelbak
The tracker bit can be used as follows:
1. It updates its location every 1-5 minutes to a web service. If the wife in the OP has the app on her phone she can see where you are now, or failing that where you were before falling off the grid
2. She can use the app to immediately find you right now using the web service, or failing that:
3. She can call the phone number for the sim card. It will ring twice then hangup and text back a location with a map link that opens in google maps. If it doesn’t ring she can see where you were when the device last uploaded its position.
Edit – forgot to say that the battery life is a good 24 hours when set to update every 5 mins.