You're fine on the 20 year rule here -- we count it as inclusive of the years starting Jan. 1, so anything that happened in 1997 is fair game here. It would drive us nuts trying to do this by date.

I don't know if I can be much help as I'm not that familiar with the British side of things, but John Carroll's A Concise History of Hong Kong talks a bit about the reaction in Britain. For the British, it was definitely seen as the end of not just the British Empire, but of worldwide British influence, and the rise of the Communist China's influence. During the negotiations over the handover, the British delegation worked hard to make sure that the PRC would guarantee that the people of Hong Kong would have the right to vote. Margret Thatcher was the first world leader to meet with the PRC after the Tiananmen Square Incident because of the negotiations. And as we know, it didn't completely work out the way the British wanted it to, and they agreed China's One Country Two Systems policy, where China agreed to let Hong Kong rule its own political and economic institutions as an SAR, or Special Administrative Region, for 50 years after the British handover. So you can see even in just the negotiations, Britain didn't have the leverage anymore to negotiate a favorable deal with China, a pretty big contrast in comparison to how Britain got Hong Kong and the Kowloon Territories over a century ago. Carroll doesn't discuss the reaction of the British public, but I can imagine that they were just as unhappy as the British officials to see Hong Kong go back to China, a communist country, without guaranteeing them the right to vote. As a last ditch effort, the British allowed the people of Hong Kong to attain full British citizenship before the official handover occured.

Carroll's account of the handover ceremony seems to reflect this attitude as well. The British farewell ceremony was solemn, with a teary speech from the last British governor, who mentioned that many of Hong Kong's people came as refugees fleeing a Communist regime, and a gloomy rain setting over Prince Charles' speech, which promised Hong Kongers that Britain would not forget them. (There seem to be a few Youtube videos of these speeches that you might be interested in, but I'm not sure if it's exactly what you're looking for.) But once the British left, the new Chinese government celebrated with fireworks, a symbolic end to the "Century of Shame." So I'd say generally, the public probably would have reflected the same general attitude of sadness and a bit of nostalgia as expressed by the officials.

Hope this helps!

Edit: grammar