I used the Crimple Hall, Harrogate chargers a week ago with a ~45% full, cold battery, and got 90kW for the first few mins. Charging to 80% took less time than to walk into the store and buy/drink a can of coke.
TL;DR - The lead on a standard Tesla Supercharger is plenty long enough for an MG4. Note that to stop the charge and release the cable, you press the button on the connector.
The trick for Tesla destination chargers is to look at the colour of the associated sign.
White will work with an MG, red won't