Hello all,
Thought I’d mention this in case it’s helpful for others.
I have a stupid house - there’s a conservatory on the back, the next room in is a bathroom, and a small hallway to the kitchen. I’m in a terrace house, so there’s one way I definitely can’t go!
Because of this arrangement, there’s never been any ventilation of the bathroom 
So after some mulling over, I bought a compact “Mechanical Ventilation Heat Recovery” unit (MVHR), instead of a normal fan - being aware of energy prices and all that. Also because I don’t want to blow perfectly warm air outside when possible!
Marking out time - having to avoid lintel over window, and top of conservatory roof, but as high as possible in the bathroom.
Angle grind (diamond edge disc) off tile
Damn, should have cut “L1” in there, hehe.
Now time to see how cheaply they did this bathroom…hmm, just my luck.
Hey ho, that’s what multi-tools are for, now we can see the external brick leaf
And through (looking from outside)
The cores and tools FYI
Test fit
Skipped a bit, cut through side of conservatory, put ducting in (laser is because I need the pipe to have a fall down to outside, in case of water/moisture build up)
cut to fit
bathroom before final fitting
new vent and hood sticking out of conservatory
Hope that’s of interesting to someone, if it doesn’t work as hoped, I’ll switch it out for a normal extractor, there’s another place that this unit would work and at least the ducting is in now.