Ivan,
Did the selection myself last year. Bombed out on the sim stage. My colleague in the sim made it through and is now flying with JMC. From the twenty (approx) initially only four made it to the sim and only two made it on the scheme.
Yes it is worth it, but think long and hard about the lack of cash while training. If you have the offer of a turbo job at the time it is better to take that from a short term finacial view.
And £250 quids is a lot to spend if you crash out at the first stage.
Best of luck,
Vigi