<h1>Calculate Your Potential Revenue</h1>
<form id="revenueCalculator">
    <label for="postcode">Select Postcode:</label>
    <select id="postcode" required>
        <option value="">--Select Postcode--</option>
        <option value="E1">E1</option>
        <option value="E2">E2</option>
        <option value="E3">E3</option>
        <option value="E4">E4</option>
        <option value="E5">E5</option>
        <option value="E6">E6</option>
        <option value="E7">E7</option>
        <option value="E8">E8</option>
        <option value="E9">E9</option>
        <option value="E10">E10</option>
        <option value="E11">E11</option>
        <option value="E12">E12</option>
        <option value="E13">E13</option>
        <option value="E14">E14</option>
        <option value="E15">E15</option>
        <option value="E16">E16</option>
        <option value="E17">E17</option>
        <option value="E18">E18</option>
        <option value="EC1A">EC1A</option>
        <option value="EC1M">EC1M</option>
        <option value="EC1N">EC1N</option>
        <option value="EC2A">EC2A</option>
        <option value="EC2M">EC2M</option>
        <option value="EC3A">EC3A</option>
        <option value="EC4A">EC4A</option>
        <option value="N1">N1</option>
        <option value="N2">N2</option>
        <option value="N3">N3</option>
        <option value="N4">N4</option>
        <option value="N5">N5</option>
        <option value="N6">N6</option>
        <option value="N7">N7</option>
        <option value="N8">N8</option>
        <option value="N9">N9</option>
        <option value="NW1">NW1</option>
        <option value="NW2">NW2</option>
        <option value="NW3">NW3</option>
        <option value="NW4">NW4</option>
        <option value="NW5">NW5</option>
        <option value="NW6">NW6</option>
        <option value="NW7">NW7</option>
        <option value="SW1">SW1</option>
        <option value="SW2">SW2</option>
        <option value="SW3">SW3</option>
        <option value="SW4">SW4</option>
        <option value="SW5">SW5</option>
        <option value="SW6">SW6</option>
        <option value="SW7">SW7</option>
        <option value="SW8">SW8</option>
        <option value="SW9">SW9</option>
        <option value="W1">W1</option>
        <option value="W2">W2</option>
        <option value="W3">W3</option>
        <option value="W4">W4</option>
        <option value="W5">W5</option>
        <option value="W6">W6</option>
        <option value="W7">W7</option>
        <option value="W8">W8</option>
        <option value="W9">W9</option>
        <option value="WC1">WC1</option>
        <option value="WC2">WC2</option>
        <!-- Add more postcodes as needed -->
    </select>
    <label for="rooms">Number of Rooms:</label>
    <input type="number" id="rooms" min="1" required>
    <button type="submit">Get Estimate</button>
</form>