London in the gray months of January and February is a different kind of trip. The flights are at their cheapest, the line for the British Museum barely exists, and you can spend a rainy afternoon by a fireplace eating a proper Sunday roast. It is the best time to see the city without dodging the summer crowds.
Big trips like this take some planning, and how you spread out the cost matters just as much as booking the right week. We can break the $3500 typical US cost into manageable pieces so you are not scrambling to pay for everything at once.
That intro window is a hard deadline, not free money. If you still have a balance left when those 15 months are up, interest kicks in on the remaining amount.