The paper about Standing Committees appears to assume that the amendments are ones which have been put forward by MPs, rather than ones which have already been passed by the House of Lords, where the Bill was introduced.

I'd imagine that might change the proceedings a bit - for example, the paper talks about them having the right to decide which amendments to consider, and I can't imagine that would apply in these cases, since unless and until the Commons throws them out and the Lords accepts that, they are surely part of the Bill.

If any of the MPs on the Committee are the MP of Mudcatters, that might be useful. MPs are generally supposed to read letters from constituents, and not from constituents of other MPs. I don't know if a different rule applies when they are being approached not as constituency members but rather by virtue of being Committee Members. But anyway faxyourMP only works for your own local MP.