Why was the policy not paid out when your sister died? I keep thinking I'm missing something, as to why it's beautiful to buy a life insurance on a grandchild, with the parent as beneficiary; it just seems weird. What spurred the insurance company to move, at this point? How have they determined that you should be the beneficiary, rather than you mother? Perhaps by the terms of your fathers will? Then, there's this lump sum payment, and your stated enthusiasm for gambling... careful. And, I'd consider working part-time, too, if I already had, or soon would have, a house fully paid for.
Anyway, congrats, and good luck.