I may be mistaken but isn't nic now limited to 32mg/ml instead of the 72mg it was? If so this is a blessing in disguise for a loop hole. Sell bottles of 'concentrate' and then stock and sell only 1 nicotine flavour, plain. That's 1 thing that need to be TPD compliant. Sell these as nic shots, do multiples of 100ml combined sales and then have the nic shots watered down to 30mg/ml. 90ml concentrate and 1 shot is 3mg 80ml and 2 is 6mg and so on.
That seems like the best option as its a completely legal Fuck you!