One tip from me: I wrote my abstract after the conclusions, so that I could use my most important conclusions in my abstract. Basically I took the first paragraph or so from my intro chapter, added a bit about historiography (existing research) and methodology, then summarised my chapter structure, and summarised my final conclusions, basically drawing on the final paragraph of my last chapter. It was written in just a few minutes that way, rather than agonising over it. And I did the really important thing in an abstract, which is to emphasize your contribution.
Good luck for the last push! If you can just keep going for a bit you can have a massive rest afterwards :)