Set aside a judgement

Description of legal work: I need help to set aside a county court judgement. It was served at my previous address and I did not have chance to enter a defence.
I would like to get this set aside and put a defence in. The judgement was entered by a solicitor who I engaged for my divorce, after a catalogue of errors I engaged another solicitor. I did complain to the original solicitor and have this along with their response.