Born in Winchester, Tonks was raised in Andover and attended John Hanson Community School in the Hampshire town.
His footballing journey started at Andover Town before he moved to FC Salisbury United as an under-eight.
While at Salisbury United, he also joined Pezzaz Street Soccer, a Futsal team, and played for both.
He also represented his district and county.
He was scouted by AFC Bournemouth from district football as an under-13 and signed for the club that season.
Initially earmarked as an attacker player, he was converted to right-back at the beginning of his season with the under-16s and started his two-year scholarship at the beginning of the 2021/22 season.
He started all three games as the Cherries reached the fifth round of the FA Youth Cup in 2021/22, providing the assist for Daniel Adu-Adjei to open the scoring in the 2-0 win against QPR in the fourth round.