I am a fellow IT sufferer and "Just have to fly" career changer
From the perspective of somebody purely in the wanabee camp (still doing PPL) and so very inexperienced but having asked all the questions you are asking (and more) to a reasonably wide range of aviation folk here is my synopsis:
I would say at the moment, there is no need to quit anything. You have the req'd no of hours for a CPL and a whole lot more! A modular ATPL course is pretty cheap at £3000 or less. Whilst doing the ATPL if you gather IMC and Night quals and if you can a multi rating too in prep for the CPL training. With those and an FI(R) qualification and you can possibly make a half-decent living as a PPL instructor whilst you decide how to tackle the IR or wether to build on your current FI rating. Whats that in cost? £3000(ATPL)+£1500(Night)+£1000(IMC)+£6500(CPL)+£6000(FI(R)) = £18,000. The IR will set you back at least another £14,000 but I do not belive that is required if you follow the instructor route initially. I think you are in a good position regarding the money:risk ratio as you don't need to suffer the expense of initial training and hour building
However, one thing that has dawned on me is that when I eventually am qualified and am able to make the move I WILL be earning significantly less than the £prettygood+car+pension that I am currently on. I would therefore assume that so will you. Not putting me off. Nothing drains the lifeforce more than having to do something you hate everyday whilst knowing you could do something you have dreamed of doing
Hopefully I am not talking ***********. Good luck dude
Kef.