Oh this is getting really interesting now. Though I hope there wont be a "real" Nefertari.
If she really wants to take responsibility for changing history she shouldn't try to go incognito though.
Now while it's interesting that she can go back and forth in time, the time passing in her original time while she's in ancient Egypt seems to be way shorter than the other way round. She returned after the Nile celebration so 3 months equal 1 week in her timeline.
How long did she wait to return that 4-5 years passed? If 1 week in modern England equals 3 months in ancient Egypt, she's either been idling in England for 5 months or the time difference is different when she goes from modern England to ancient Egypt. One way or another she can't do this to often or she'll just end up in an ancient Egypt after Ramses II is already dead.