The winning team only from the group will progress to July's finals in Estonia.
Harry enjoyed a fine season with six appearances and first senior goal for us in the Europa League, before switching to Millwall in January for a succcessful loan period in the Championship where he scored 10 goals and was named Millwall's Young Player of the Season.
Now he's determined to fire England into the finals.
"The main thing is that we qualifgy for the finals and if I can score a couple of goals along the way, that would be great, a perfect end to the season," he said.
"I think they will be three different types of games.
"Slovenia will press us high and they've a few decent players who can punish us if we don't stick to our game plan.
"I think Montenegro will line-up with plenty of men behind the ball and look to hit us on the counter-attack.
"We then finish against Switzerland and they are a good technical side, like us. I'm sure they will go for a win as well, so that will be a decent match.
"It's always good experience to play international football and to see what level you are compared to other countries."
The Young Lions compete in the Elite Qualifying Round of the UEFA U19 Championship with matches against Slovenia at Preston's Deepdale tonight, Montenegro at Rochdale's Spotland on Sunday then back to Preston for Switzerland on Wednesday.