It's a tough one Simon,
I think you know the answer but like me you just want to make sure you have thought about Everything.
Rent your place out here first, if you can get a good price by doing that , I would do that for a year or so, and by then you would know if the Phil's is where your heart is, if it's not ,then just move back here,
Lots to think about but sometimes we think to much about it too,
Good luck its hard I have changed my mind many many times already, yes we are still going to make the move but I try not to think about it to much now,just keep putting the money away, plus our house is being rented out at first ,just in case