Try the Pennine Bridleway. There will be places you have to push or carry, but that's par for the course if you want natural off road. Otherwise there's the Trans Pennine Trail, Leeds Liverpool, , Rochdale Canal.
For a natural feel without the tech fest I would suggest the Dales. Big wide bridle ways and limestone grassland trails. Again, there will be places to test and challenge, but the open spaces and wild feel will be there. Similarly the N Yorks Moors. The old Iron Railway routes around Pickering, Whitby, etc all great epic rides.