Possible to return to a PhD years later (at the same or a different uni?) Here's my challenge: I took a suspension of studies about a year and a half ago from my UK PhD program (in ancient history) and moved back to the US after my funding ran out, and now have to decide whether to pony up for part-time tuition or just drop out entirely. 

I have no hope or interest in pursuing the PhD for a career; I've got a career in an unrelated field. But my subject and my thesis add something to my life that I don't want to give up. But I'm not eager to dump $10,000 for just part-time tuition when right now that would be a doable but poor financial decision, especially since I doubt my rate of progress would improve. I've finished about 50% of my thesis.  

Is it possible to just quit and then reapply again in the future? It's never been stated outright, but the vibe from the university is it's finish or quit forever. I don't really care if it's at the same university or not. (As long as it's not in the US; I have no interest in a longer than 3 or 4 year program). 

Has anyone else left a program only to complete it or another one years later?
Whether your university (or another) will allow you to pursue your course in a particular fashion is something you will have to ask them.

The key question to consider though is how your research will be impacted by the delay. I guess ancient history may move slowly enough that it's unlikely someone else will do the research while you are waiting. But how well will you be researching while doing something else/after you haven't thought about your topic for a long time?

A more common approach in your situation would be to transfer to a shorter qualification (some sort of masters) that you can complete reasonably easily using the work you have already done.