GazG,
You have to decide what it is you want. I 'be been lazy and not seen if you've posted earlier, so excuse me if you've noted it somewhere in this thread.
It comes down to planning for the future as well as your immediate goals. Finances are I presume not infinite, therefore, which option puts you in the best position? I would say an MSC as with an engineering MSC your setting yourself up very nicely, whatever you decide to go on and do.
If you've thoroughly researched the industry, understand what it's like to be a commercial pilot and will accept the enormous sacrifices it will take to get there, then a few hours in a plane is neither here nor there (but of course would be fun). If its the FPP you've your eye on, then chat to people who've passed selection and get preparing now... everyone who has passed the FPP selection, I guarantee, worked theirs backsides off, so make no mistake you'll have to do just that to get through. If it does not work out this time, you'll get more chances, but that MSC might just come in handy in the meantime...
Good luck in whatever course of action you decide to take.