Tinytoessize4, for someone with that posting name, you have mighty big feet
Why is it so hard to see the following?:
A) You and you alone have assessed the 'worth' of the right of way to your neighbour.
Unsurprisingly to to your advantage, you have assessed this right of way as inconsequential.
B) You have decided that contrary to what every document I have found on the matter in my brief searches, and that of others, the fact that she has not used the access means that her rights of access have lapsed.
Although convenient, there is not a shred of available evidence that this is the case. But don't worry, by the time you have waited another 20 years (at least) to prove her abandonment of her easement, your son will be out of your family home, so the problem may no longer be present.
C) You have made huge assumptions that your initial letter to your neighbour was a polite formality, and that in fact you were doing her a favour by fixing her wall
D) You fail to see that whatever the odd nature of the joining of your homes on the first floor, joining the two homes will devalue her home by making it a semi-detached house (or even terraced - you don't make mention of whether there are other adjoining properties).
I can think of no other way to say this, other than you must be a terrible law student!
What is your current predicted grade? And what area do you intend to practice in? Because I hope it is one where people's lives aren't affected.