So I have a self build Mendel Reprap style 3d printer.
I've not used it in sometime after moving house but I'm looking to use it again. What should I pay attention to before calibrating and running it again?
The main thing that might have changed is the bed level, so you should level the bed again. If your printer is sufficiently sturdy, this may not even be necessary (but this should become apparent during your first print). The remaining calibration parameters (steps per mm for all axes, PID tuning, etc...) should not have changed.
You should perhaps also check for any bolts/nuts/cables that might have come loose during transport. This is not particularly likely to have happened, unless something was loose to begin with.