Two things - first I don't think it's finished yet. Second, don't even think of taking the motorhome up there (and I'm not just saying that because I'm a wuss). There's a fabulous little bus route that goes round there via Whinlatter and Buttermere, the 77 or 77a depending on whether you go clockwise or anticlockwise . But they only use a little bus and they only do it in summer. So if they don't do it in anything big or in bad weather, I respect their judgement.
Edited to add - I'm planning to do it next July, for a milestone birthday!