S.F.
If you dont completely want to wean try and pump as much as you can before you leave. Maybe whoever is watching your baby can feed her brest milk and switch with formula.
I did that for my baby when I went out of town. When I was gone, I would pump and through what ever I had down the drain so that I wouldnt dry up. My mom gave my daughter my milk and would supliement with formula at night time.
Or that might be the best time to wean. A friend of mine went out of town for a weekend and weaned her son. Just remember you will be in pain!