It depends a lot on who your MP is. If your MP is in a safe seat (a little under two thirds of them), they have no reason to do any more than post back the party response. If your MP is a government minister, they cannot do any more than this on any national issue which is outside their personal portfolio.
If you live in a contested constituency and your MP is not a minister, you are likely to receive a more substantive response. However you should not expect them to have access to a subject-matter expert; an MP is one person with a staff of around four or five office workers.
If you live in a contested constituency and your MP is not a minister, you are likely to receive a more substantive response. However you should not expect them to have access to a subject-matter expert; an MP is one person with a staff of around four or five office workers.