NATS selection process seems very limited, competitive, long and demanding.
And the problem is what? NATS wants to recruit the best that it can, why wouldn't they? If you're not keen on working hard to get what you want then, with the greatest of respect, maybe this industry isn't for you.
Oh, and getting in somewhere as an ATSA may work but it's hit and miss, I know many ATSAs who would make good ATCOs but have never been given the chance.