New outside light using RADAR

I am looking to replace the outside light at the side of the my house. Currently it is a halogen floodlight with PIR fitted to the front of my garage. As is often the case, water has got into the PIR and destroyed it.  I remember reading about cheap doppler RADAR modules that can detect movement through walls and wondered if I could use one of these inside the garage to operate like the PIR floodlight did but keep it in the dry.. I would also like to update to a LED light.   

The RADAR modules are the RCWL-0516 available from Amazon UK for £4.99 for 6 there is no need to use a microcontroller as these can be configured without one, however I am planning to use one as  configuring the modules require the soldering of small passive smd caps and resistors which I am finding more and more difficult these days. I won’t require many GPIO pins, so I will probably use an Attiny85 or similar MCU. I will also need a relay or relay module. Time to get the breadboard out again….