I wear Hotter trainers - they are the only shoe that I have found will fit the orthotics. Sandals are not a possibility, even ones with backs.
The NHS ones not only seem hard but the raised bit is in the wrong place for the arch of my foot and is quite uncomfortable. Also it is just a "half foot" and the edge is uncomfortable where it stops. They were measured by me placing my foot in a shoebox full of solid sponge and thus making a cast of my foot.
The private ones were measured by laser, giving a 3D measurement. The private ones are hard underneath, but have a soft insole which goes right down to the toe of the shoe - so no sharp edges. They are infinitely more comfortable, but it may be a poor operator, and the NHS ones elsewhere might be fine. I went for the NHS ones first and only moved on to private when I found them unsatisfactory.