Funds Available for Trade (FAFT) is made up of Available Funds in your Cash Account plus unsettled sell trades minus unsettled buy trades and open buy orders.
Your funds available for trade also depends on the settlement date of your trades.
Your sell trade proceeds are available to you to fund buy orders or trades as long as settlement date of the sell is on or before the settlement date of the buy.
For example the sale of Australian shares (t+1 settlement) on Monday can be used to place an order for shares in the UK (t+2 settlement) on or after Tuesday only.