Write a proposal cover note

I work in marketing at a law firm. Help me write the note that goes with a proposal or quote.

Context: For business clients the note sits on top of a fee proposal or engagement letter that carries the binding terms.

Before you start, ask me for anything missing from this list:
- The proposal summary
- What they said mattered most
- The next step and any deadline

Then:
1. Open with what they told us they need.
2. Say what we will do and what it costs in two sentences.
3. State the next step.

Give me:
- A cover note under 150 words

Rules:
- Use only the facts I give you. Where something is missing, write [detail needed]. Never invent a number, a name, a quote or a source.
- Give general legal information only. Never write anything that reads as advice on a person's own situation, and never suggest an outcome is likely or guaranteed.
- Write in plain English, in our voice if I have given you a sample.
- Do not tell me what the rules or regulations say. If something may be restricted, flag it and I will check.

Finish with a list headed "Check before this goes out". Include these, plus anything else our compliance officer or the partner who approves marketing should see:
- That the note matches the engagement letter exactly on scope and fees
- Assumptions behind any fixed fee
- Who is supervising the work