Hey there, I have an iPad with iOS 12 on it, but I prefer the iOS 6 look more, and I don't want to jailbreak my iPad, where is a good place I can get the themes?

If you want your iOS 12 to look like iOS 6 (including icons, app interface etc.) then it’s impossible without jailbreak.

I don't suppose that an iOS 12 jailbreak is coming by anytime soon? I too have an iPad that's running in iOS 12.1 and I intend to jailbreak it.

Some have claimed to break 12.0.1, but nothing on 12.1 yet (from any legit groups). Apple closes loopholes with every update, and does pretty much everything in their power to stop jailbreaking. If you actually want to jailbreak your device, avoid updating and save your ssh blobs.
The easiest way to do that is through this site:
https://tsssaver.1conan.com/

Still have an SE with ios 9.3. And a 5C with ios 7.1.2. Both jailbroke heheh. Need to fix my ios 10 5s, app support is dwindling.

No, you must jailbreak your phone. Custom themes require root access.
Even jailbroken, the ios 6 themes of the days still weren't perfect. I could never get the icon sizes right, and many portions of the os remained unskinned. Plus most themes use Anemone nowadays, and that's trash compared to how well Winterboard worked in the pre-ios 7 days. Probably due to how IOS has changed.

As far as IOS 12.1 jailbreak Alibaba always has one but they sell their exploits to the highest bidder (Apple), as does everyone else who finds one.
There is a safari exploit for <12.1.1, so someone could write another jailbreakme site if they find a way to use it to install substrate, provided the exploit provides root access though it works mostly for macos anyways (and jailbreaks are more complicated than that). Then there's the sandbox escape one but still <12.1... Either way, IOS 12 carries a lot of optimizations and patches (lots of anti jb ones btw). If you can, stick to the lowest ios 12 build you can get, which is sadly 12.1.1.

Try this

https://www.idownloadblog.com/2016/05/1 ... jailbreak/

That only creates safari shortcuts on the home screen. Then again, jailbreak themes can't change that much either nowadays.