Just to update anyone who might need it, I visited my Mercedes dealer today.
He said that I will be looking at a delivery date of early next year (ordered in June). He said Mercedes have come off the scheme for Q4 to get through the sheer amount of Motability orders they have, and aim to come back on the scheme in Q1 2022.
They don’t think the chip shortage will run into the end of 2022. A Class and GLA are most effected but if you want a bog standard one they can get you one within a week (if you are willing to swap your existing order). Mercedes are also not allowed to sell any cars in their show rooms just those on the forecourt as they can’t replace them.