Welcome to the forum
The problem is easy to remedy, and comes down to the use of constrained dates and the way project calculates dates.
Calculating dates- project looks at the project as a whole, and the start and finish dates are the dates the first activity starts and the the last activity finishes, by default (you can change that, but dont worry about it for now). So in your case, the start date is the date of the first 7 day notification. The end date will change if you add another block of work and make it start later, when the end date will be revised to the day that "resident satisfaction form" is finished.
With constraints, it is important to make sure that you understand how they work. A task that starts as late as possible will work BACKWARDS from the finish date of the project, and adjust the task accordingly. If you put a task in that alters the end date, then any task with a "start as late as possible" constraint will automatically jump forward to fill the gap.
You have used 3 constraints - line 2 "7 day notification" is as late as possible, line 3 "Scaffold erect" is " no earlier than" and line 11 "PV removal" is "as late as possible".
I assume that "scaffold erect" is the driver for each house, and the 7 day notify is a reminder. In this case, I would tend to change the link so that the notification occurs 5 days before erect (a negative lag) for every unit after the first (The first stays as it is so that the original 5 day wait is maintained).. Generally -ve lag isnt good, but in this case it is a sensible option. Moving to "PV removal", this seems to start as soon as scaffold erect is done, so it wants a "as soon as possible" constraint to bring it in line.
SEWI enabling works can be linked from scaffold erect rather than a lag link form 7 day notice if you pre
Finally there is the scaffold erect "start no earlier than". From your info, I guess that scaffold goes up on one house, as soon as its done you move to the next, and so on. In this cae, I would use a "start no earlier than" and link scaffold erection from the previous scaffold erection. This would mean that any delay in scaffold would put back the any following erections, which is as it should be.
THE SHORT VERSION
Change all constraints to "as soon as possible", and link scaffold erect from the previous scaffold erect. Make 7 day notification a successor to scaffold erect with a negative lag. Enabling works are linked to scaffold erect as start to start, not 7 day notification.
If you have a gap between houses, just put a lag on scaffold erect.
this provides a programme that will allow for any scaffold delays during progress, giving a truer finish date.
I have enclosed a sheet showing the revised programme, which works as you want it I believe.(Zipped, as it exceeds the upload limit)
Pleae post back if this isnt what you wanted, and w can look at it again
hope it helps, and sorry for the long explanation