With two countries of similar tax burden, it's easier, might as well just subject yourself to full UK tax, and NL might be become disinterested in the details if there's little left for them to grab under DTA.
It's worth trying to get social taxes paid in your home or country where you expect to accumulate enough qualifying years for a state pension - and not the uk (where I expect state bankruptcy will preceed receiving any pension!) - I think it's form A1 to opt out of UK NI and pay in NL.