Re: From twice to eight times 'Super Earths' or ...
Sorry, we didn't invent the term super-Earth, but others have run with it.
Simplistically speaking a super-Earth is a planet that's thought to be rocky, but is significantly larger than Earth. If you look at our Solar system you have the rocky planets (Mercury, Venus, Earth, Mars), the Ice Giants (Neptune, Uranus) and the Gas Giants (Saturn, Jupiter). To first order these classes are distinguishable based on their measured density.
NGTS is looking for rocky planets (as deduced from their measured density), but fundamentally is limited to finding planets that are ~2x Earth radius (ie. 8x Earth mass assuming Earth density).
That's about the best that can be done from the ground. Finding 1x Earth radius / 1x Earth mass planets is really only possible from space, and that's ~100x more expensive. A small number have been found, but they are in short-period orbits, and unlikely to be habitable.
If you're really looking for true analogs of our Earth (ie. a 1 Earth mass planet, in a 1 Earth year orbit about a 1 Sun mass G-class star), then the space missions mentioned here (Kepler, TESS) are not capable of detecting these. You will have to wait until PLATO flies in 2024, then wait maybe a decade after that for its findings to be verified.