The midfielder has been name-checked by manager Enzo Maresca as one to watch for Chelsea fans this season.
"I always enjoy my time with England," Harrison told chelseafc.com. "It was a great learning experience and a good few days.
"We played in a friendly tournament, which was a good opportunity because it allowed us to see how the squad gelled together and gave us the experience of playing against other nations, which we haven’t done in a while.
"One of my favourite parts of playing for England is competing against different countries and teaming up with players from other clubs. I get to play alongside top players from various backgrounds and it’s a great experience."
Harrison also said: "We played three matches in one week, so the time away was intense. But it’s good because it keeps the momentum going and gives you a taste of the senior game, where you might have midweek fixtures along with weekend games.
"Playing against other countries is always a big challenge because every nation has its own style of play. Right now, we’re going up against some of the top players, so the competition is tough, but playing against the best only pushes you to work harder and improve.
"Playing for England is a bit different from playing for Chelsea, where I know how everyone in the squad plays. That’s the hardest part, you need to bond quickly with the England squad if you want to perform at your best.
"The experience also gives you a chance to improve your game and provides insight into what my future could look like."