Someone recently asked me a question about thermal ablation and pregnancy after age 40. I'm not an expert, but here's what I found from this article:
http://www.tubal-reversal.net/blog/2009/tubal-ligation-reversal/tubal-reversal-endometrial-ablation-pregnancy-concerns.html
If you still have bleeding, then your chances of pregnancy increase. However, it looks like any pregnancy after ablation must be carefully monitored due to the possibility of abnormal implantation. The consequences can be quite serious. The bigger issue seems to be implantation -- if there's no soft spot for the embryo to land, then it can't implant.
I think your best bet is to consult an OB. Unfortunately, from my experience and others, doctors tend to be very pessimistic about conception in your 40s. Should you conceive, see an OB right away.
I think if a woman wants to try, she should. Like any woman trying to conceive, a back-up plan for life after ttc and a rationalized end date should help in coping with the fertility roller coaster.