Welcome to the forum! Others will chime in as well but first - get a bigger case. Mantis gets advised often as it's pretty good value for money. You can say now you want to start small. But a modular setup grows and you'll be happy not to be stuck in 84hp after a few months. I can vouch for that - I wanted to start in 84hp and I'm at around 400hp now, a year and a half into it.
Then, about how modular works. To get a note, you need a trigger (note NOW please) and a note value. The Ladik 610 will give you some note values from the CV out. But it also needs a trigger in. So you'll need a clock source and/or sequencer of some kind. Take a look at Pamela's New Workout (or Pro Workout). It features a clock and several kinds of organised triggers. Call it a clock-and-sequencer if you like.
So now you have your Plaits clone getting a trigger and a note value. The good thing with Plaits is that it can take a trigger - it saves you some complexity of adding VCAs and envelope generators. Plaits output isn't ready to listen to, though. How are you going to listen? Headphones? Connect to the line in of an amp or powered speakers? In any case, you'll need an output module. I started with the Befaco Out, which I thought was a good little module. There's plenty of others, like the higher end Joranalogue Transmit 2 in case you need XLR out (you probably don't).
With those 4, you'll have a basic setup: triggering notes, setting the tone, and sending it out. You still don't have filters or effects. And with other oscillators, you'll need VCAs and envelopes. And there's a billion options for sequencing as well, internal as well as external (Beatstep Pro is a good starting place for an external sequencer for modular). But if you want to start really small, it will work fine and give you plenty to explore.
