Get the post office to connect your line, they wont charge you at all (or at least not as much as BT) then stay with them as their line rental is cheaper than BT anyway. BT tie you into a 12 month contract, the PO dont so you can change providers at anytime

They will always use BT engineers to activate the line in the exchange.

Im very surprised at the timescale BT gave you. Its normally 11 days max!