I don't think Tolkien's real life would make a terribly exciting or profitable film anyway, though an unfussy TV drama might work, if done subtly by the BBC or someone like that. Tolkien was known for his pranks, but he wasn't really Johnny Knoxville or Steve-O and stealing a bus wouldn't be so thrilling to today's audiences.
But I'm also seriously wary of this film idea too. I think it will give the wrong impression to people who are never going to read Tolkien's Bio, and many people rely on films to tell them stories they cannot be bothered reading. However, if it is
very silly and obviously not true, then I might approve more!