Depends if it's a diesel or a petrol engine.
Did around 50 miles on 0 in Captain slow mode in my Golf, filled with over 50 liters after that.
Once did a similar thing in a Renault, started coughing at about 40 miles after 0... wouldn't start at first crank after filling... took a while to get the air out
I wouldn't want to do more than 30-40 miles in a petrol or 40-50 miles in a diesel after it says 'empty'.
PS: Is it really that bad in the UK, because we've got Covid in the EU but no fuel shortages... makes me think no. 10 is making stuff up.