Resources

The microbit.org page should be your starting point for all-things-micro:bit. It includes a getting-started tutorial.
The micro:bit Accessories page has categories for:

1. 1. Protective plastic and silicone cases

   2. Displays: Larger LCD screens and display panels

   3. Edge Connectors & Adapters

   4. Electronics: Elecfreaks Lego construction, Automation for home low-voltage systems, BitMaker adapter to use micro:bit (3.3v) with Grove (5v) connectors (ultrasonic distance sensor, fan, motor, servo, RGB LED strip, Slider), DIY Robotics Driver Breakout

   5. Environment Sensors: CO2/Temp/Humidity, Atmospheric pressure, UV, Soil Moisture, Dust, Water temperature

See how you can Use the Arduino Integrated Development Environment (IDE) to program the micro:bit

Where to Buy

US

Parallax: Micro:bit v2 Go bundle ($20 each), 3.3 v micro servo motors ($6)

Sparkfun: UV sensor ($3), Environment sensor ($22), micro SD data logging board ($14), pulse oximeter/heart rate ($12), Soil moisture level ($7), Weather station ($18) or full Climate kit ($120)

Adafruit: Motion ($10), C02/temp/humidity ($50), Submersible water pump ($3), Larger display screen ($18), Robot Car w/proximity sensor ($30), Translucent protective case ($3), Lego compatibility kit ($99), Plant watering ($10), Micro servo motor with position feedback ($15)

Robotshop: Traffic Light ($5),

Eduporium: Air quality kit ($40), Solar Experiments Kit ($50)

STEM Education Works: (Kits for smart Agriculture, City, and Health, (about $60 each) though the sensors in those kits can be bought elsewhere.)

UK

Kitronik: Micro:bit v2 boards ($14 for board only!), Micro:bit v2 10 student classroom pack (w/batteries and cables ($160), 8x8 LED panel ($21), Control slider ($10), Game controller ($16), e-paper ($29), Traffic Light ($5), 1 octave piano ($20), Streetlight ($60), Air quality kit ($45), Line-following car ($28), Moisture sensor ($3), Smart greenhouse kit ($45), OLED display ($14), Servo motor driver board ($11), Robotics kit for 11 devices ($484), Continuous rotation servo 360 degrees ($5), Micro servo ($3)

Pimoroni: Bit:2:Pi adapter for Raspberry Pi boards ($20)

China

Elecfreaks: Wifi extension board ($17), Laser dust sensor ($30)

Seeedstudio: There is a wide range of Grove sensors, requiring a micro:bit v2 Grove shield ($11). Once that shield is attached, Grove sensors can be used. Many of these are both highly precise and expensive. For example they have extremely accurate barometers, Biomedicine sensors (Heart Rate, EMG, Fingerprint), Distance Sensors (Ultrasonic, IR, LiDAR, Doppler Radar from 30mm up to 12 m), Gas sensors (O2, CO2, Alcohol), Light sensors, Communication (RFID, GPS, RF, Long Range, NFC).