I finished my first play-through of Dawnguard's main quest a couple of days ago and I was going to come on here, just to say how much I enjoyed it. I didn't do every side-quest and I'm seeing a lot of talk about Lost to The Ages. I don't know anything about it but the response it's getting seems very positive, to say the least.

My quick question is, can I still begin Lost to The Ages, having finished the main quest, or will I need to get it next time around?

For the record I sided with the Dawnguard.

Thanks in advance.

It's just a side quest with nothing to do with the Dawnguard. So yes you should still be able to do it.

Cheers man, that's all I needed to know.

There is a very noticeable white book added to the game with Dawnguard, you can start off with that, or just find the new location while exploring.