How to determine phase and neutral on a wall outlet?
Quickest way is to turn off the mains and unscrew the socket and determine the polarity by the colours (Blue being NEUTRAL and brown being LIVE).

Otherwise if you have an EARTH connection nearby (copper pipe for instance) use that to determine which one has the highest RMS voltage from EARTH. Neutral shouldn't be that far off EARTH while LIVE should be 230V (ish) 

(this is also why I like the British mains plug)