Personally I don't think going the private route is worthwhile, your far better off waiting til recruitment starts and doing that. If EGCC is your dream then the private route will give you slim to not change of getting there as NATS likes their contollers to be NATS trained so they know they are getting the best. The only way of going to MAN then is to work at a non-NATS airfield and hope NATS get the contract for it and request a transfer. From what I hear though the jobs for non-NATS airports are hard to come by and it's often ex-NATS who get the jobs as their training is of a better standard.
I'm not trying to put you off going that route, but make sure you do a bit of research and go visit many units and find out where they prefer to recruit from (non-NATS units) I'm guessing liverpool will be the closest for that and they are pretty good!