People have said the obvious, so I'll do an outside suggestion at a team based over in Ireland. Obviously league's rather small there, but I reckon there's enough to go around.
Assuming I won the euromillions or what have you, I'd try and get league into schools, get it on television, just try and get youths interested in and playing the sport. I think there's a potential goldmine with the GAA, as they're an amateur sport so there's no financial draw for them, and they tend to develop excellent ball skills. Would be a very slow start but I'm rich in this timeline so I can wait. Once it starts growing I'd fund the setup of mens, womens, 9s, touch, all that good stuff. Only once there's a base to build on would the Dublin Wolfhounds be launched, initially probably relying on foreign players, the goal would be to bring in natively grown players. Longterm this would hopefully make Ireland itself into a somewhat competitive team on the international level.
Give me 30 years and funding and combined with the other poster's plan for Wales and there'll be the grounds for real, competitive international matches up north.