Send everything you have. The more Roger can see at the outset, the faster and the more useful the first answer is — and it costs you nothing to send it now.
What happens when you press send. Your papers go straight into secure storage. Roger runs the conflict check at the same time. He does not open the papers until that check has cleared — so sending them early cannot prejudice you or anybody else.
If a conflict shows up, the papers are deleted unread and you are told in writing that they have been. Nothing is retained and nothing is passed on.
If it clears, and it almost always does, Roger comes back with a scope, a quote and written terms — having already read the file, not having asked you to send it twice.
He can tell you what the engineering question really is, whether it can be answered from what you have, what else would be needed, what it is likely to cost, and how long it will take. That is the part most people want and rarely get up front.
He cannot give a technical opinion on your collision until he is instructed and has worked the evidence, and nothing here is legal advice. An expert's duty is to the court and it overrides any duty to the party paying.
Roger runs a vehicle and automotive engineering practice and a separate mediation practice, and he knows the people who cover what he does not. If your matter needs a different discipline he will say so and, with your agreement, introduce you to somebody who does it properly. You are not sent away empty-handed.