Building an excel spreadsheet to show NPV and IRR

General information for the business: We are a new business working in property development
Kind of support: Cash Flow
Accounting software: Excel
Description of support work: I have built a spreadsheet to calculate cost, income and viability assessment on property development projects. I need this validated and improved, specifically whilst apartment sales can be forecast commercial units, car parking, ground rents etc are valued on a capital and I need to be able to reflect this into the IRR
Extra notes: Within the attached spreadsheet the input cells are highlighted in yellow and the numbers in red text.