This sounds pretty much like being an events organiser for craft fairs etc
https://www.ukcraftfairs.com/organising-and-running-arts-and-crafts-events
Try the above for starters then run a search for events management businesses etc, and look around for the websites / social media of assorted craft fairs, Comic-Con’s etc - have a good nose around for their trader application forms and see what questions & terms they have listed
Volunteer as a helper at one, or trade at one (as you’re not interested in trading yourself then try and find someone who does and offer to help them at one).
With this if you arrive early and leave late then you may pick up more of the behind the scenes actions of arrival/setup/pack/leave
You do need public liability insurance - and also an idea as to whether you will have ‘proper’ traders thus require them to have their own PLI as well or if you are encouraging ad hoc crafters who have not got that far and need to consider further insurance to cover them
You will be committing to the venue, so you pay the full cost hoping to cover that in income.
Measure the venue, work out how many tables you can fit (allowing space behind and between as well as public walking space in front). Divide cost by the number of tables and you have a starting price - if you fill the room
Remember to think of the tables.
Does venue hire include tables & chairs, or do you need to hire them ?
(Some traders will use their own tables, some will use the provided ones - decide whether you will charge less for an empty space and extra for tables)!
How long do you get access to the venue before and after your preferred event time?
You need to lay out the tables, check in people traders and pack away after (ask traders to stack them during pack down but not everyone will and you are still responsible for putting them away / giving them back to the external hire company if applicable
Set realistic trading times, and rules on
when traders can arrive, the time that they must be ready by and importantly that they cannot pack up during trading times nor can they move stock in/out during trading times
You are also responsible for advertising the event to both the public and for sourcing traders.
Consider extras - why would people bother coming? Have some entertainment and catering
Think of parking and loading access.
If there are multiple car parks then pick the customer parking and trader parking
Set rules that traders are to move vehicles before opening
Check for height restrictions and how to get the key to open a van height restrictor gate.
Some traders arrive by car (I know one who fits her whole stock & table set up in a mini), some in small vans / transit vans and some will have a high top van
The two sisters that I go to comicons with use a high top long wheel base transit van. There are two event organisers giving them very different experiences
One is often calling them asking them to book specific events, but when venue access & trader parking is brought up the organiser often shrugs as it’s ’not their problem’ - in which case a tight venue is the traders problem - and they won’t be paying to attend that event to be stuck unable to unload nearby or park - if the answer was “there’s only a couple of big spaces so we will reserve one” then
A different organiser investigates access, sets time slots if loading space is limited, finds parking and designates trader parking and / or flags up any need to park further away / parking fees etc
Guess which one is the traders preferred choice
If you’re overwhelmed with traders then your laughing, but it you need them to come then you need to make it worthwhile and attractive