Olaplex treatment would turn back time on your hair. Needs to be done in a salon though. Redken heatcure hair masks are very good for a home treatment if you get dry ends.
Skyn eye gel patches are an excellent temporary fix for brightening and plumping the area under your eyes. Put a packet in the fridge and use them for 10 mins before doing your make up. They're brilliant.
Look after your hands and nails with a cuticle oil (I like Essie apricot oil and burt's bees lemon balm) and a hand cream. The red top neutrogena Norwegian hand cream is unbeatable imo and hand chemistry pro repair hand cream is pricey but very very good at making your hands look brighter and smoother.
Count is right about the lifestyle changes. They make the biggest difference. I'd add cut out refined sugar to the list. That has quite a dramatic effect on my skin.
Skincare wise you're not going to make any permanent difference in the time you have unless you get non-surgical cosmetic procedures done like Botox etc and I wouldn't do that in a hurry without fully researching and thinking about it. You're better off, at this point, in focusing on hair and make up with things that give an instant boost like face masks or primers.
Tbh, a hair trim, treatment and blow dry, a fresh manicure (you could do that yourself) and your outfit will be enough to make you feel more confident and fresh.