How much space do you have and are you interested in DCC?
What would you like to see in your layout, e.g. stations or industrial scenes, city or country?
You probably want to think about what your eventual aim is and to buy stuff which will help you get there. You've got a fair bit of money there and probably want to have a good think about what it is you want from your layout. Don't let it burn a hole in your pocket and buy something on the spur of the moment.
Look at track plans books and get some ideas about bigger layouts if you have space or better uses of space if you don't have much. If your interested in DCC, one of the new Hornby DCC starter sets would be worth thinking about.