Agree with dzug. Thurs before Good Friday is a nightmare! Leave plenty of time! Main problems will be Preston - Manchester area,( but not a lot you can do about it), and Birmingham area. You have a few options here, but keep an ear out for travel reports. You could cut west to the A449 (accesible from M6 J's 13 or 12 ) and follow it through Wolverhampton, Stourbridge and Kidderminster to join the M5 at J6 near Worcester, but this route could be just as bad! You will just have to make the decision on the day.