As said above, development finance is usually taken on retained or rolled interest, meaning that there are no monthly payments for the borrower. The lender will place a charge on the land/property for the percentage of the property value they are lending you, for example, if you are borrowing 50% against land valued at £100k, the lender will place a charge on the land for £50,000.
This figure is known as your gross day 1 loan and it is what you would owe back to the lender at the END of your development loan term but only for the portion of the loan borrowed against the asset. Your net loan is the amount you actually receive on day 1, which is lower. The lender (or a good broker) run a calculation to find out what figure would grow into the £50,000 once interest and fees have been added to it. Lets say for round numbers that a £45k loan would carry £1k in fees and £4k in interest over the term of the loan, in this example £45k is your net loan and this is the amount that you receive on completion, most often used towards the purchase of the asset.
The other part of your loan in development finance is your works facility, which will cover the cost of the works for you, as a net loan. The gross loan for this portion is the cost of works plus the fees and interest associated with this portion of the loan only. For example if the works are to cost you £100k and this carries £3k in fees and £7k in interest, your gross loan here would be £110k and your total gross loan would be £160k, using the land loan in the paragraph above.