I think you've gotten some good ideas so far. While money is almost always an issue, I do not sense that it is THE issue here. This hobby can be done very inexpensively, as the many students and DIYers can attest.
It seems to me that your fear of failing to grow your plants is battling your enjoyment of a planted tank. This is a natural dichotomy and the way to tame it is to simply accept failures as part of the hobby. You are intelligently anticipating that you have too much light for no CO2, so okay, adjust your lighting or add floaters. Change your plant selection.
You certainly have enough gear and knowledge to have a rewarding setup and it sounds like the rewards will be as welcome as ever. Good luck to you and your cat.