You will lose next to no oil at all, don't even need to jack it up at one end, just jack as normal or on a lift etc, the oil lives at a much lower level at the rear of the sump.
You can use a woodscrew into the seal and draw it out a little at a time working arond the edge, or just very carefully with a screwdriver flip the seal out.
Try to replace with a VITON SEAL, as these are way better than the ford rubbish, cost about £9 a seal.
The seal will have the number 42-56-7, on it as this is the inner/outer/width dimensions.
tabetha