Tricky one.... As its not in the bathroom (specialist location) more falls under best practice... Would may be of put means of isolation further away and slightly higher than the mixers..
At the end of the day I can't see building control being involved if your just refurbing your bathroom.. If you do pop a seal isolate at the consumer unit..
to refer to "522.3.1 A wiring system shall be selected and erected so that no damage is caused by condensation or ingress of water during installation, use and maintenance. The completed wiring system shall comply with the IP degree of protection relevant to the particular location.
NOTE: Special considerations apply to wiring systems liable to frequent splashing, immersion or submersion." makes far more sense than giving a set distance.
Bathroom looks brilliant