You can get 70% loan to value on the plot and 75% loan to value on the projected sales price of the completed properties. If you are a first timer the bank may want an independent monitoring surveyor but may allow your architect to have that role.
The business loan will in staged payments with a drawdown as the while the plot is being developed its going up in value.
Steer clear of Barclays as they are the sons of Satan
Nat West/RBS I highly recommend