It's not much appreciated, but the Microbit V1 is an nRF51 and the V2 is an nRF52. Download the SDK from Nordic Semi [0], grab a copy of ARM GCC[1] or Segger IDE [2] (free for nRF5x, complete with drag'n'drop firmware upload [2a]) and you have a powerful Bluetooth LE/2.4GHz radio/LED blinky development environment (whatever platform you're on).
[0] https://www.nordicsemi.com/Software-and-tools/Software/nRF5-...
[1] https://developer.arm.com/tools-and-software/open-source-sof...
[2] https://www.segger.com/products/development-tools/embedded-s...
[2a]https://www.segger.com/products/debug-probes/j-link/models/o...