After two years at the Madejski Stadium following a move from Llanelli, the 21-year-old is heading back to Wales.
The fly-half's spell at London was somewhat of an eventful one, which included an Aviva Premiership relegation battle and arguments over who he was eligible for internationally.
He says his time in England was very beneficial for himself but looks forward to heading home on a three-year contract with Cardiff.
"The problem from a personal point of view, signing so early, there are boys that have got two or three years here and the coach might choose to give them more game time. It's frustrating, but hopefully I can push on in my career," he told Sky Sports.
"I think moving has definitely given me a good foothold for the future. If I didn't move from Scarlets two years ago, I wouldn't be the player I am today. You never know, but I am really happy with how things have gone and the player I have become.
"When I came over to London I didn't know how to cook a meal or wash my own clothes, so in terms of living-wise it has been great. Playing-wise, I have played over 40 games and for the national team. I have enjoyed working with some top-class coaches and working with great players."
Before he thinks about his summer move, Shingler first has to prioritise the end of this season with Irish. Three important fixtures lie ahead in Worcester, Sale and London Welsh starting with the St Patrick's Day clash with Warriors this Saturday.
He said: "It's all looking exciting, at the top and the bottom. At the bottom, you don't want to be there, but being mid-table is boring so we thought we would get ourselves at the bottom. We got ourselves in this mess and we have to get ourselves out and push on.
"I played in last year's (St Patrick's Day) game and it was a great day. Hopefully the boys in our squad can rise to the occasion, and I've not doubts that they will."
Despite the fact he is soon to be moving away from the club, he has faith in those around him to keep the Irish in the Premiership in this campaign.
"There is a lot of youth in the team. Marland (Yarde) is playing very well at the moment. It's still a young team, young coaching set-up and there will be a few more boys coming in. I know it takes time and results take a bit longer, but hopefully the teething problems are over and the team can push on," he added.
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