Set form action based on a previous selection

Hey!

I have a calendar vue component in Laravel and I need to be able to set a form action dynamically - based on what a user selects...

so - I have a select input (outside the form) that a user would select a site from:

<select name="sites" id="sites" class="tw-border tw-border-grey-400 tw-p-1 tw-rounded tw-block" v-model="siteInput" @change="updateCalendar">
    <option value="">Please select a site...</option>
    <option v-for="site in sites" :value="site.id">{{ site.name }}</option>
</select>

Once they've done this, it updates a calendar - and they can select the day they wish to book.

On the booking form that pops up, I need to submit it through to a specific url - based on the site id they have selected above...

for example:

<form action="/sites/1/visits/create" method="get">

Vue is quite new to me, so I'm at a bit of a loss on how to achieve this. Apologies if I've not posted enough info - happy to clarify where needed, but this is it in a nutshell!