Most people agree that Thatcher had many faults, the a point of debate is what would have happened if Labour had remained in power?
Manufacturing would have slowed down regardless of who was in government, emerging economies in the Asia had already started to eat away at our large scale manufacturing base. Like it or not our inefficiency was not helped by the unions. Ineffective management didn't help either.
On the sell off most of the huge nationalised industries were union-dominated, under funded, inefficient and massive loss makers. It would have cost billions to drag them into the modern era - so to sell seems like a prudent cause of action.
With regards to mining - it could not compete with coal from other countries, it importance was massively overstated due to the high profile that Arthur maintained due to regular threats of strike. The numbers of miners had declined significantly over the previous twenty years.