I assume you know BBVA no longer offer loan products catered to flight training like they used to.
Other large loan products available are secured against an asset, usually a property. These are quite widely available however to my knowledge the interest is quite high.
As mentioned above, there are other training options (mostly modular) which would allow all training to be achieved potentially for much less than £80k-£100k.
Have you considered a modular route? A PPL can be achieved in your spare time along with work, along with hour building. A smaller (but still large) loan could then be used to fund the final required training.