I'm a lucky girl: I will be receiving £1,000 for my 50th birthday from my in-laws

. I currently have a Canon EOS 450d with kit lens and a 55-250mm zoom. Should I: a) upgrade the camera (I'm thinking a 60d), or b) stick with the 450d and buy lenses and other bits such as a flash gun? Or even a single, super duper lens?
I'm a keen amateur with an eye to moving into a semi-professional arena....
Advice, please?