Rees qualified in fourth position, just 0.3s off pole. He was able to podium in both races and finish round one as joint championship leader on 36 points.
"I guess it was like a feeling of we'd made the right choice," he said.
"The choice was to sacrifice everything we had to travel across the world and race in the hardest domestic championship in the world. But it also lit the fire that I wanted more, I want to win."
Round two of the championship headed to Snetterton, where Rees put in an impressive performance in qualifying to sit ninth on the grid, despite the high winds hampering riders.
Rees finished 10th and after the opening three races of the championship he was holding on to third overall, 19 points behind the more experienced championship leader Tom Neave.
The iconic Silverstone Circuit hosted round three and Rees' qualifying time earned him second spot on the grid.
In race one he got off to a fantastic start, managing to lead into the first corner. This was the first time Rees had led a race in the UK.
By mid-race he had dropped back to fourth position, eventually missing out on the final step of the podium by one second.
After the race Rees said: "I'm really happy with the race, of course I would have loved to have been on the podium, but P4 finish is great toward overall championship points."
In the second race of round three Rees finished sixth, leaving him in third position overall in the championship, 36 points behind leader Neave.
The fourth round was at the Oulton Park circuit.
"Literally nothing can prepare you for how insane that place really is," Rees said about the course.
He finished race one in 17th to record his first no-score of the season and slip to fifth in the championship.
Race two saw Rees make an explosive start, managing to pass five riders by the end of the opening lap and sitting 12th. By the start of the penultimate lap he had moved up to 11th, which he would hold until the finish.
Rees now found himself dropping to sixth in the championship, 70 points from the new championship leader Chrissy Rouse.
Round five of the championship returned to Donington Park, where Rees had enjoyed success earlier in the year.
Heavy rain and high winds saw the morning qualifying session cancelled and replaced with a 10-minute warm-up, limiting Rees' track time for the weekend.
He began race one from 12th position and made a great start until he made a mistake which dropped him back, eventually finishing the race in 19th.
Race two of the weekend was held on a completely dry track over 24 laps. Rees started from 22nd position but going into the Melbourne Loop for the first time he crashed, landing hard on his right shoulder and ending his race early. After five rounds of the championship Rees was now in eighth position.
In the week prior to the final round of the championship Rees undertook laser and hyperbaric treatments to speed up the healing process of his broken AC joint.
After discussion with the team, he made the difficult decision to sit out the final round of the championship to focus on recovery and being fit for the 2021 season.
Rouse held on to be British Superstock 1000 champion, finishing the year with 181 points.
Looking back over his rookie season, in which he finished eighth overall, Rees said: "I think it went really well, obviously without the injury on my shoulder at the second-to-last round it could have been better but to leave there with two podiums and finish inside the top eight in the championship - I believe I should be proud of what we achieved this season.
"Round one at Donington was a huge highlight for me. Never in my wildest dreams did I think that I would stand on the podium in my first race at BSB, and then to do it again in race two really cemented to me that I am pursuing the right path."
Rees has now set his focus to be fit and ready to take on the challenge of being a championship contender in 2021.
