Bathroom extractor fan/can't vent to outside

[TeaAndToastest]

We are about to redo our bathroom. It currently doesn't have an extractor but does have an opening window.

We live in a conservation area and the bathroom is at the front of the house, which is a terrace. We aren't allowed visible external vents on the front of the house.

DH is keen to get an extractor fan but I can't see how we do it. Surely it would need an external vent? Am I missing something? Is there anything else we could do?

Can you have a ceiling fan and duct it through to the rear of the building or a roof tile-vent?

Thanks very much for replying. I don't think roof would work as it's a three storey house with bathroom on the first floor.

I don't really understand how you would duct to the back of the house? Is this something you could do inside the walls? Is it a huge job? (Apologies for the dim questions- this stuff is not my forte.)

Our bathroom at the front of the house vents up into the roof and out the back of the roof.

Vent it to the side. Or maybe there is some sort of air brick/disguised fan vent you can get if you google.

In my house one of the fan vents runs though a ducting between the floors. I think this is pretty common, although probably would be expensive to retrofit.

You can duct beneath floorboards, behind stud walls, through ceilings. It's worth having an electrician look at your house. We built a cupboard in our 1st floor bathroom to hide ducting that needed to go through the roof (on top of 3rd floor) via the eaves on the second floor, as our house is grade 1 listed.

The longer the run of pipework the less the extractor works so you would need to take that into account. I will put this video here on extractor options and do any of your neighbours have the same layout as you? Do they have extractor fans?