Honestly, I'm doubtful that's the rationale. Because you can buy e-liquid in 10 ml containers, that could equally be spilled as well. I believe it's more a general regulation across the board to try and limit the amount of e-juice and nicotine a vaper can use at any given time.
I think some of it makes no sense, though I guess there was some concerns raised over spillage, but really that's more likely to happen when refilling more often, and there's also the 20 mg/ml limit on e-liquid. I am of the belief that TPD was more worried about general CONSUMPTION of e-liquid/nicotine though I'm not sure the regulations actually reflect that-- as one is able to purchase more liquid and refill more frequently, but my GUESS is that TPD was trying to set some (rather unenforceable, though a pain in the neck) guidelines concerning how/how much e-liquid should be used.
I'm far from an expert on this, but I'd be highly doubtful that having 3 separate chambers that "link" to the atomizer would be able to gain approval in any case, and it seems (to me) even more complicated than just refilling one's tank in the first place?
Just my opinion of course.... I have no way of "linking" this idea to anyone relevant in England, though you might want to run this idea by the UK forum to be found here:
UK Forum
Best of luck,
Anna