Both answers fit together: one local listing log, one completed-sale investigation, and one simple acquisition-and-operation model. Repeating that monthly would build a useful body of notes.
For a first purchase, keep a running questions list beside the model. Unknown tenure, access, repair, occupancy or shared-area matters should not disappear merely because the spreadsheet still produces a positive result.
The person responsible for each cost matters as much as its amount. Add a column for owner, occupier, shared, or unresolved, then confirm the actual position on any live deal.
Good list, but avoid false precision in the Manchester comparisons. A carefully formatted estimate remains an estimate. Short notes explaining uncertainty are often more valuable than extra decimal places.
A monthly recap could separate facts from interpretation: what was newly listed, reduced, withdrawn, relisted or confirmed completed, followed by members’ views on why. That would preserve the distinction everyone keeps emphasising.
For mortgage comparisons, the property itself may affect whether two options are comparable. Keep lender discussions tied to the same unit or clearly state when the security and occupancy assumptions differ.
Maintenance timing deserves a line in the cash flow. The same total cost can have a very different effect if required before occupation rather than spread across later years.
I’d add a brief reason for including each comparable. ‘Same area’ is not enough; state whether the match is based on occupancy, tenure, size, condition, configuration or some combination.
This has produced a workable starting routine: define a small Manchester area, separate vacant from tenanted and mixed-use units, preserve dated listing histories, investigate completed figures cautiously, and model costs and delays explicitly. The unresolved facts should remain visible rather than being converted into convenient assumptions.