I have obtained the information from Timatic
A further question is whether it would be possible to get a UK visa in my Turkish passport, to avoid any such ambiguities in future.
You could try talking to the Pakistani Embassy to find out if presenting a British passport at the same time as your Turkish one might count as "having a British visa". It might depend on the exact legal definition.
Getting a UK visa when you are already a UK citizen is going to problematic, even if it is possible, and may make someone suspicious of why you are doing it. You could also try to obtain a Schengen or US visa with your Turkish passport, both of which should be possible. It's also possible (though not necessary) to obtain a US visa with a British passport.
However the point of the exercise seems to be to avoid getting a Pakistani visa in advance - but to do it you have to apply for another visa (in advance). Unless there is a really good reason it would seem to be simpler to just apply for an advance visa from Pakistan.