Are my (Theoretical) calculations correct?

ChrisJR90

In the next coming months, we will be looking at making a purchase. We have been researching as much as possible (new build and FTB), I have made a few calculations and just wanted to double-check I am not WAY off and that I am on the right tracks. Putting aside product/legal fees and any other one-off associated costs with mortgages. Do my calculations look to be on track? (changing the rate where needed and adjusting accordingly)

5% - 85% LTV			10% - 80% LTV
Deposit:	£15,000.00		Deposit:	£15,500.00
Contribution:	£14,997.50		Contribution:	£14,997.50
Equity Loan 5%:	£14,997.50		Equity Loan 10%:	£29,995.00
Total Deposit:	£44,995.00		Total Deposit:	£60,492.50
Mortgage Needed:	£254,995.00		Mortgage Needed:	£239,457.50
Rate - 2.11% (Interest)	£448.00		Rate - 1.74% (Interest)	£346.00
Mortgage Payments:	£857.58		Mortgage Payments:	£760.59
EL Repayment:	£250.00		EL Repayment:	£500.00
Total Payment 5 Years:	£1,107.58		Total Payment 5 Years:	£1,260.59
Total Equity (5 Year):	£69,569.80		Total Equity (5 Year):	£85,367.90
Remortgage Needed:	£185,425.20		Remortgage Needed:	£154,090.60
Rate - 1.91% (Interest)	£296.00		Rate - 1.79% (Interest)	£229.00
New Mortgage Cost:	£676.01		New Mortgage Cost:	£552.70

PS this is based on a sale price of £299,950.

I also understand that the equity loan will be based on the valuation at the time of paying back the loan and could go up. 

Any advice would be appreciated