TPA is good advice. There are outbound UC flights in Feb for as low as 29,000. Unfortunately, the return is considerably higher. One-way UC cash fares are super expensive, and you might baulk at my workaround below.
You could fly Feb 13th UC to TPA for:
*58,000 points
*1 x credit card voucher
*£1495.00
But now we need to get you all home... We're losing 46,000 value from the voucher here.
So, option 1 would be Premium points with VS. Premium is around 20,000. We could get you there UC out and PE back for 2 pax for ~59,000 points and a credit card voucher. You'd need to go cash for the 3rd.
You can get cheap one-way fares with people like Norse, but I've never tried them, and god knows what their financial health is like, so proceed cautiously.
It's also worth noting that the T&Cs of the CC voucher restrict upgrading two people one-way. Even if you were lucky and found an agent who didn't have a clue what they were doing, I'm not sure this would help you, as you'd still all need to get back on one-way cash fares.
Finally, if all 3 of you are set on Upper, the return fares on points are a joke so you're going to struggle and cash might be your best option. As a minimum, you could book a PE return with points, use the 75,000 voucher to upgrade to Upper. That at least means only cash fares for 2.