With modern wiring on the lighting circuit it should be fine to replace a shaver socket with a custom hard-wired hairdryer. You may need to uprate the power rating though, which is a simple job, if your lights start to fuse.
A very good hairdryer / shaver socket combo is available for around...
A legal hair dryer and shaver socket is available. I have used them in hotels. If you look up [removed] you will find a wall mounted hair dryer with built in transformer and a shaver socket outlet.
If you already have a shaver socket it almost certainly has a built in transformer. The...