How would I create a select element with the 14 days from today as options
You're close! If there's one thing I've learned about Twig, it's easy to overthink it... 

Create an array with the first date, then merge the rest of dates into the same array with a for loop. Just increment the day in the range:

 {% set rangeOfDates = [ now|date("l dS F Y") ] %}

 {% for i in range (1,13) %}

     {% set rangeOfDates = rangeOfDates|merge( [ now|date_modify("+" ~ i ~ " day")|date("l dS F Y") ]) %}

{%endfor%}


Then in your forms macro:

{{ forms.select({
    options: rangeOfDates
}) }}