I have attempted to 'search out' but failed miserably, so can anyone show me exactly where I can safely lift and support the 'rear' of my '02 hatchback as nowhere looks substantial enough?

Many thanks

 

The sill area isn't the best and can flex with the jack under it. So what I do usually is place it under the hub axle. If jacking both sides I chock the front wheels. Make sure to use a trolley jack as the one provided is cat.

 

i've always jacked my Focuses (plural?) on the sills with no issues. Although i would advise caution if you're jacking towards the rear of the car, as the sills can rot and you will make a mess.
As per the answer above, underneath the hub is a good alternative, or even on the subframe if you can jack the jack underneath with enough travel.