We had the same warnings. I suggest you keep the EGPWS on and don't, never, appart from flying into known mountainuous area and being VMC, shut it off!
If you quickly have a look on the Jepp charts, you'll find [B]both[B] QFE and QNH altitudes written on the side of the charts, STAR's, approach and even SID's. The matter is to have a look at the field elevation, convert it with the QFE given into QNH (add 1 hPa per 30 feet of elevation). When first contacting approach, ask them for QNH and compare with what you have. It is usually within 1 hPa anyway.
Then when ATC clears you to and altitude in meters QFE, you don't care, you compare the meters into the QNH on you Jepp chart and that's no more calculation!
Have a good flight!