Oh dear, well, he is looking at sizeable driving ban, guidlines suggest around the 2-2.5 yrs mark and unpaid work. High risk offender with the DVLA i think also.
He could get a solicitor but could use the duty solicitor its just mitigation really that they could help with if he is planning to plead guilty. If there are good ways to introduce mitigation a solicitor can do that for him but really all he can do is be remorseful, take a few character letters and take it on the chin.
That was a high reading, he was three and a half times the legal limit. The punishment will be a severe one. At 4 times the limit your question would have been "how long will he go to jail for?"
His driving ban will be significant, he may wish to reflect on his relationship with alcohol in that time