Just a quick update on the current progress, which may help others in using the GPS module:
Firstly I started off with the Adafruit Flora GPS parsing example, and used this to become familiar with the GPS library.
I then based my code to start with around this to output current location and a hard coded destination to the Serial Monitor
My next step was to output "You've arrived" if the two matched and ":( Not home" if you haven't" This was very patchy, so I decided I needed to implement the next step before continuing. This was to work out the distance between the current and destination points, as this will then allow an accuracy to be introduced, the goal is reached when you are within 20meters of the destination.
To do this I looked into the haversine formula to workout the distance between two points, I found a lot of useful information here: http://www.movable-type.co.uk/scripts/latlong.html
As I was started to code this formula into my work, my husband informed me that he already had it coded as a C function and kindly sent it to me to save me from typing it out again.
So with this complete, I was somewhat disappointed when the distance to my destination was wildly out. It was then I realised that the GPS position was in degrees minutes and seconds whilst the function was comparing two decimal degrees points.
I searched online for guidance and found that this post on the Adafruit blog was really useful, http://forums.adafruit.com/viewtopic.php?f=25&t=30776
So I used this to understand the procedure required and then implemented it in to a function convertGPS.
The serial monitor is now outputting this:
22:16:36
Current location: 51.xxxxxx, 2.xxxxxx
Destination: 51.xx, 2.xx
Distance to destination: 8.73
Bearing to destination: -36.40
The first line is the time
The second line is the current location from the GPS (After conversion)
The third line is the destination (currently hard coded)
The fourth line is the distance to the destination
The fifth line is the bearing to the destination, this currently isn't reliable, I will need to use the compass to obtain an actual bearing back to the destination
I've attached my current sketch (with destination edited), although currently it is reasonably unformatted and commented, just a work in progress and some experimentation.