Even if Hinkley C were run by a UK firm, even if its costs were reasonable, this would still be a really stupid project.
Not all nuclear plants have run smoothly - e.g. the Windscale fire, the Chernobyl disaster, Three Mile Island, Fukushima, etc. They may be designed to work smoothly but even the best engineers and designers cannot anticipate all future problems.
In Britain the prevailing winds are from the west. Hinkley is in the far west of southern England. In case of a fire or other disaster, the pollution would inevitably spread over the Severn and Thames areas, covering major population areas such as Bristol and Reading, through to London. If the wind shifted a bit, cities like Oxford and Cambridge, Birmingham and Luton, or Southampton and Portsmouth, etc, could be affected.
Why don't these clever clogs just look at a map?!