Unless I'm mistaken, the Hawk is 30 years in service this year. Given that equates (in simple terms) to the RAF in 1977 using an aircraft from 1947! - is there a replacement on the horizon, if so, what?
Thats a very simplistic view to say the least.
Quality of build and the ability to 'futureproof' designs were completely different in 1947 to they were in 1977.
But to answer your question, I believe 24 new Hawks have been ordered and will be with the RAF some time in the future.