The UK had a smaller foreign-born population than Australia, Canada, and New Zealand. The foreign-born population in Australia, for example, was roughly double that of the UK as a share of the population.
You could remove just enough brick at hinge positions to glue a block of timber behind frame to provide enough timber for hinge mount without reducing overall width .
Or a more powerful fan so it clears the duct effectively .
Does is have timer function ? Without it the fan can’t clear the duct .Lagging the pipe will also help reduce condensation forming .