Connecting a fan to shower power

[tirfor]

Hi all, a newbie requiring advice.
I have been asked to fit a fan within a bathroom with the following constraints:
1. fan needs to work in daylight when light is off.
2. ideally on a timer so steam can be removed after showering.
3. humidistat not to be used as past units did not work to well.
4. be able to use 3a fans.
5. cheap as poss so no expensive fans or expensive pir's

So i have thought it would be best to connect the fan to the showers power.

My question is:
1. Is this ok to do or is there a better idea?
2. A timed fan requires a live and switched live, so is a fused spur available with twin fuses?
3. My idea is to tap into the supply side of the shower switch to provide the live feed and then tap into the load side of the shower switch to provide the switched live. Both lives will go to separate fused spurs (located in assessable attic) then both spurs will be connected to an isolation switch (in wall be bathroom door) then of to the fan. Is this ok or am i missing something?

Cheers for your help.

 

[Dan]

I'm just bumping some threads in the Electrical Forum, don't mind me while I do this, you don't have to respond to them. Although if they are still current topics, and you do wish to reply, you're welcome to. Keep the thread on-topic and make sure you stick to the forum rules though.