Bathrooms are classified as special locations and are divided into separate zones, zones 0, 1, 2 and outside zones. The bidet must be installed in an outside zone to meet current wiring regulations, the outside zone being classed as at least 0.6m away from the bath or enclosed shower and 1.2m away from the shower water outlet if the bidet is to be installed in a wet room.
Any electrical work undertaken in a special location will need to be tested by your electrician and a minor works certificate issued.