The BBC series, Dickensian, did a good job at filling in some of the back stories to a number of female characters, including Lady Dedlock and Miss Haversham - the latter as a strong and confident businesswoman, before (inexplicably) falling for a cad. There's nothing new in the idea H&M idea at all.
In fact, I hadn't realised before today that there's a 2013 novel called Haversham by Ronald Frame. Again, we have a "feminist" Miss H, a cunning. businesswoman, whose newly fictionalised background just doesn't chime with the ending we know is coming. The reviews are interesting, and largely reflect the same argument - that you just cannot reconcile a sympathetic, feminist style character in the early years with the woman Miss Haversham decides she will become post jilting. Not without creating a much different plot and timeline than the original novel.