Nope it's you are seriously overstimating USA and UK position, the american will hurting seriously if the French don't pay the debts even because if Paris do that, Rome will do the same, the UK is even in a worse position economically and frankly she want have German and communist in front of Dover like a lung cancer.I think you are seriously overestimating France's position in 1918/19. Them going 'nuh uh' to its debts is going to enrage the British (the only friend France has left after russia caught a bad case of communism) and piss off the Americans who aren't going to be extending an economic lifeline to france again for a long long time
France will have to try and enforce any terms it puts on Germany (likely plummeting into a civil war thanks to the terms France wants) alone, with no money in bank, a chunk of the country shattered by war, its male population gutted and exhausted, and the only other great powers of note still standing either indifferent to it or furious at it.
I'd give it a few years before France has to pick those debts back up with interest if it wants to get back a seat at the international table
Does France need UK support? Sure, can London or Washington dictate their terms in such manner...only in bad fanfic because there are limit at what any goverment can accept and neither country are that powerfull to not feel the consequences or have the capacity to act on their own in Europe, so again your little fantasy of London and Washington dictate the term that Paris need to found acceptable for the ToV is that a fantasy