Albert Einstein died in 1955, having lived in the United States since the 1930s. Stephen Hawking was born in Oxford, UK in 1942. He was therefore only 13 years old when Einstein died. I can’t find any record of Einstein being in the UK between 1950 and 1955 (when Hawking would have been between 8 and 13). The only UK visits I can find were pre-1933, with his famous one being in 1931.
Given that his death occurred whilst Hawking was very young, and that they were probably never within 200 miles of each other, we can pretty safely say that the two never met.