Ya big girls blouse,get in there with yer probes whilst standing in a bowl of salty water .every time i get close to hooking one up to mains power running a relay blink sketch with a meter ready i get reminded of my own mortality and chicken out
Alternatively get an isolation transformer,or bodge your own with 2 transformers wired back to back,240 v in the primary of 1 transformer the secondly wired to the secondary of the second transformer,should give you enough volts and current on the primary winding to power the board,its will still give you a kick if you grab hold of live and neutral,but no shock risk to earth and the current will be limited so no big bangs if your probes short something out