Car battery time – who online or pop to Halfords?

The last battery I changed on the wifes car I got from Carparts4less Bosh battery for £20 cheaper than the motor factors ‘cheapie’. I did not have the radio code so I connected jump leads to my car then the wifes car. Then disconnected the battery with leads still attached to clamps then connected new battery. Voila battery changed without loss of power to car and no need to get code for radio (son helped keep clamps on leads at changeover). HTH