Autobuy Sweep is a feature that enables the automatic withdrawal of your Autobuy directly to the BTC withdrawal address registered on your account.
Normally with an Autobuy, the Bitcoin purchased is added to your Coinfloor Bitcoin balance.
By enabling Autobuy Sweep, future Autobuy purchases will be swept directly to your registered Bitcoin withdrawal address. This doesn't affect any BTC balances already held in your Coinfloor account.
This means you can send GBP from your bank account and receive Bitcoin to your registered Bitcoin withdrawal address.