Best practice for Horizon View is to have a separate vCenter for your VDI workloads (your 30 desktops) but it's not mandatory. You mention remote access over VPN. If your users are on the VPN they would be able to operate just like a local machine on the network so you could just publish the URL for the connection server(s) or a Load balanced VIP.
To access the environment remotely (no VPN) you would want/need at least one UAG (unified access gateway) to broker connections to the internal connection servers or VIP.
If you don't currently have licensing for Horizon take a look here at the VMware store for a rough idea of what 30 licenses would cost for the different models, Standard/Advanced/Enterprise.
I hope that helps.
Thank you so much Joe for getting back.
I'll start going though the labs and then setup a test.
A separate VCenter license for such a small number of VMs seems a waste though,
All the best
Check the Horizon editions and what is included. Most editions include a license for vSphere/vCenter/vSAN, so you don't need to buy them extra.
Horizon is very tightly integrated into vCenter and puts also additional load on the vCenter, so it's better to have a dedicated one, even for 30 desktops I guess.