Probably only a live/switched live. However, sometimes you’ll find they’ve been wired to the switch. You’ll find three cables – power in, power out, switched output. Neutrals will be joined. Earths will be joined. Two lives into one terminal, one live (the switched live) in the other terminal.
There is the possibility that the bathroom fan is powered from it too. This will have a live, neutral, switched live and earth (3 core and earth or maybe singles too).
Main switch off! Photograph it before you take it apart. Label what comes out where and rebuild as seen. Put the plug in the sink and the bath and shut the toilet seat. (Don’t ask me how I know to do this).
Sometimes it is possible to disassemble the switch and get it working again but probably better to get a new one.
Rich.