De-industrialization was probably inevitable, but she made it much harsher than it had to be. Her governments treatment of the miners were a disgrace.
In an interview about a decade or so before he died, Michael Foot (who, for those that don't know, represented a mining area in South Wales when he was Labour leader) made the point that the really awful legacy of the Thatcher government in the coalfields wasn't the loss of mining jobs as such (which he thought was bad but - on some scale at least - basically inevitable), but the fact that absolutely nothing was done to replace the damage done by the loss of jobs in the coal industry.
One detail that I bang on about a lot (because it's important and because most people aren't aware of it) is that some of the places that suffered the most when Thatcher's policies wrt the pound and so on rendered British manufacturing horrifically vulnerable to imports (resulting in job losses on a scale - and at a speed - that's still hard to properly comprehend) in the early 1980s were actually old mining areas where manufacturing jobs had been created in the 60s and 70s to replace jobs lost in the coal industry as a result of the NCB's rationalisation programme in the 1960s. The other types of manufacturing area to really, really,
really suffer then were those dependent on the steel industry - which in the longer run extended to what was left of shipbuilding - and inner city areas, in which there was still generally a lot of manufacturing employment up to about 1980 or so. Of course deindustrialisation in many of these places started before the 1980s, but the scale and speed of things increased greatly and, taking us back to Foot, nothing was done (nothing serious anyway) to repair the damage.