B737NG Captain reported executing a go-around after encountering wake turbulence on approach to BWI.

Narrative

I was conducting IOE with a new hire FO; who was the PF. We were behind a cargo 747 for much of the STAR into BWI and were slowed for spacing behind them. There were several other flights on the arrival into BWI and there was some confusion with ATC and the arrivals as to which approach we were being vectored for as the previous two Controllers told us to expect the RNAV Z; but the Final Controller said it was unavailable and to expect the RNAV Y. We learned were going to be assigned the Y approach while 1 mile from the IAF for the Z approach; so we were not sure who we were following at this point and had to set up for the Y now. While approaching the FAP (Final Approach Point) on the RNAV Y RWY 10 (gear down; Flaps 15 and 170 knots at 1400ft AGL) we started to get what we thought was moderate turbulence in the clouds. This started to turn into rolling movements; with the aircraft rolling +/- 20 degrees AOB (Angle of Bank) in each direction. I surmised this was wake turbulence and called go around". I was concerned about getting into an UPSET at this speed/altitude. The FO immediately accomplished the go around procedure and call outs. I advised ATC we were going around due to wake turbulence. We were quickly sequenced back into BWI."