Welcome!
One of my motivations for quitting was a transfer back to HQ, after a stint in a smaller office overseas. Moving back was a make-or-break matter. I too knew it was a chance I was fortunate to have, as it would mean a career-making move if executed properly. So I completely get the "can't afford to screw this up" mentality you have.
It can be a strong incentive. Let it be just that. Listen to that voice that is commanding you to give this everything you've got.
Ultimately the journey has been even more rewarding than I thought it would be. It hasn't been completely smooth sailing but at least I know I've given it my best (sober) shot. The doors that opened were kind of different from what I expected and I've matured so much along the way. I'll NEVER regret the effort I put into cleaning up for that move.
All the best, stay focussed.
"One who has a 'why' can survive any 'how'".