Gomes was one of United's rising stars when he made his debut aged just 16 in 2017.
However, after struggling to break into the first team, he turned down the offer of a new deal to move to France.
After a successful loan spell with Boavista in Portugal, Gomes has established himself as a key man and helped Lille qualify for this season's Champions League.
He is one of a number of fresh faces brought into the squad by interim boss Lee Carsley, who has previously worked with Gomes in the England youth ranks.
"When I left (United) it was more the idea to better myself as a player and person, being (on) the journey I went through I knew eventually I'd be able to create a pathway to be in this position I'm in now," Gomes told a press conference.
"It was difficult leaving the club I was in since six and heading into the unknown really for me personally.
"From then it's been an uphill trajectory, but also with a lot of difficulties and difficult moments going through it, but being in this position now makes it all worth it."
Gomes was part of the England under-21 side, coached by Carsley, that won the European Championship in 2023.
Previously he captained his country at under-17 level in a side that contained England regulars Phil Foden and Marc Guehi.
But he said the wait for his first senior call-up has made it even more special.
"You want to play for your country as much as possible. This last couple of days has been really special and I would love for it to continue in the long run," he added.
"Playing for your country, you can wait as long as it takes, the moment you can represent them at the highest level, that's the highest you can have personally in your career.
"I (have) seen everyone do it earlier than me, but it didn't discourage (me), if anything it made me hungrier, and seeing team-mates you've played with go on to almost live your dream, you can't be any happier for them."
Carsley's caretaker reign begins away to the Republic of Ireland in the Nations League on Saturday.
Gomes' chances of featuring in Dublin have increased with Foden and Cole Palmer withdrawing from the squad due to illness and injury respectively.
Real Madrid's Jude Bellingham is also sidelined by a calf injury.
