We have pedunculate oak, but have successfully both coppiced and pollarded trees around 10-15cm diameter in an area that we were restoring to coppice and which had overstood for about 20 years (hence the size of the oak trees). We started off coppicing, but tried one pollard last year. The tree we pollarded was about 7cm diameter. We are impressed with the regrowth which is better than the coppiced oak of the previous year. This is probably because the willow, hawthorn, hazel and crab-apple has outgrown the coppiced oak because it grows more quickly and after two years regrowth is now shading it out. So we will try pollarding more oak in future. BUT we don't have sessile oak, so I can only speak for our experience with pedunculate.
I would say if you are coppicing oak, then it needs to be a stand of oak that will all regrow at the same rate, rather than mixed in with faster regrowing species.
