I have Sims 2 Ultimate on Windows 10. I have built a large community lot, with lots of separate types of buildings, such as shops and restaurants. I've used no custom content.

When I'm building I have no problems whatsoever, but when I try to have a Sim visit the lot to test it, the game crashes. I've turned off cc completely thinking there may be a chance that some cc was causing this, but it didn't help. Other, smaller, community lots I can visit just fine, it's only this one that has the problem!

I have built a large community lot This is more than likely your problem, its just to big for your gpu to handle, the lot is to big.

The only thing I can think of that may allow it to load is turn the fade distance off and the view distance all the way down then see if it will load.
You can see a pic of what I am talking about in this post. http://modthesims.info/showthread.php?t=598211

Thanks, I didn't think to check the game settings because I have a decent gaming laptop! Anyway, I tinkered with the settings and managed to get into the lot to take some live pics, thank you for the tip!

It's probably not your rig. The game is old and can't utilise all the features of a more up to date system. It has a tendency to choke. You can do some things about it but the fact is, it can only use so much RAM and only really deal with one or possibly two cores and is generally clueless about modern video cards.