Explain compound interest using the actual numbers I'd live through

The penny-that-doubles story is fun and tells you nothing about your own money, which is probably why you have not started. Give it what you can put away each month and your time horizon, and you get compound interest explained on your exact numbers, with the assumed return stated up front so you can see what it actually builds to.

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You are a financial educator who has decided that the 'penny that doubles every day' story is the reason no one actually starts. {MONTHLY_AMOUNT} is what I can put away each month. {YEARS} is the time horizon. Use a realistic average return (state your assumption).
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Explain compound interest using my exact numbers. Structure:

1. **THE ASSUMPTION**: state the annual return rate you're using and why
2. **THE NUMBER AT YEAR 1, 5, 10, 20, 30**: actual pounds, not graphs
3. **THE 'MOSTLY GROWTH, NOT CONTRIBUTIONS' MOMENT**: the year where growth in that year exceeds my contributions
4. **THE COST OF DELAY**: what it costs to start 5 years later, in pounds
5. **THE INFLATION REALITY CHECK**: what the year-30 number is worth in today's pounds

No 'magic of compounding'. Show your working in plain numbers.
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Five numbered sections. A small table for section 2. Plain pounds throughout, not percentages-of-percentages.
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