I wouldn't be too worried about it. First of all, you have to get to the finals, and Peyton will certainly help you do that. Not sure about your league, but the final in my league is week 16 of the NFL season, so the chances of the Colts being so far ahead for home field that they'd sit him in the 2nd to last game aren't that good, IMO. Have a guys with a decent match-up in weeks 16-17 just in case, but I'd get Peyton if you can.
14 Teams, each keep 14 players
QB: P. Manning, Schaub
RB: MJD, Westy, C. Johnson, A. Bradshaw, J. Ringer
WR: TO, Driver, J. Gage, Crabtree, J. Morgan, K. Curtis, E. Bennett, M. Sims-Walker
TE: Witten, M. Lewis
K: Gostkowski, J. Brown
D/ST: Tenn, NE