My next question might seem a little stupid … I have tried researching the answer to no luck. I am writing a young adult fantasy novel that will be around 120 000 words. I am certain I want an agent and wondering if perhaps I should be looking overseas? I understand from little information I could find that the publishing markets vary hugely in different countries and I am wondering if perhaps I am better off looking in USA or the UK? Like any person I would like to be able to give my book the best chance of survival and I am not positive where my novel would best be situated.
I'm going to be blunt about YA fantasy: LOTS of people are writing it, LOTS of people are putting boy wizards in it (sometimes with glasses! But, sorrowfully, not all resembling the delicious Dan Radcliffe), and you'd have to be very, very, VERY talented to try to beat Jo Rowling at her own game.
I'm also going to be blunt about fantasy in general: those manuscripts are huge. If someone wants to send me something that's 120 000 words long they would have to be very, very, VERY talented to get me to donate that much of my time to reading their manuscript. Especially when there aren't a lot of YA fantasy books being published here.
So your query about the US and UK is valid. The markets are much bigger there, and there's more likelihood of finding the right agent. But those markets are crowded with YA fantasy, and as vampires are so hot right now, it's hard for other stories to get a look-in. Which doesn't mean you shouldn't try. But just be prepared to try hard, and for a while.