Go with the Ryanair pilot's advice, invest some of your hard earned Pounds in a Class 1 medical, it's the only way that you're going to know for sure.
No two head injuries are the same, some will have lasting debilitating effects, some will be fully recoverable (I hope that you're in this group), and then there's all sorts of variations between the two extremes.
The only way to know with any certainty is to go and do the medical, NOT from an ordinary doctor who may not be aware of all of the aviation implications, but an Aviation Medical Examiner, and be totally 'up-front' about your medical history.
Good luck, and happy future flying!
Old Smokey