Thanks for your reply. Since posting, I have continued to dig deeper into the tax and have since found out that, there is a special treaty between UK and NL for pilots who work in UK and live in NL. I have been told from the Dutch tax authority that basically I would pay tax in UK despite being resident in NL and they have a double taxation agreement between the 2 countries to ensure that I don't get double taxed. I will also check with the UK tax service also to make sure that the answers align.
Regarding the app, thanks for the info, I will have a look around to see if I can find it as that would be beneficial