tyres, wheels, forks would be high on my list. you can get wicked deals on hope hoops if you look at winstanleys website. go for the standard option with stans rims and get a pair for £235. these will let you run tubeless with standard tyres which saves weight too. some great deals around on forks too, look at the revelations on the on one site, rebas on merlin i think it was, plus some good stuff on ebay at the moment too.
then sort yourself a nice cockpit out once you have an idea if theres anything you want to change about it, same with seat and post, then groupset as it wears out/deals come up
jobs a good'un