Do I need an Arduino for BLE?
The nRF8001 can not run custom code, so you need an external microcontroller to use it. However, the nrf5 series (for example nrf51822) has a microcontroller and can run custom code.

Nrf5 is Arduino compatible thanks to sandeepmistry's nrf5 arduino core.

You will need a programmer though, since the nrf51822 uses swd programming. References to recommended programmers are available here.