Looks like Arriva are going through the new driver route with some agency staff in short term reading this quote on a BBC report.

"Like all bus operators, we have suffered a well-documented shortage of drivers post-pandemic, however we are pleased to say that as of last week, we’ve a further 38 new recruits in the pipeline, plus 10 agency staff supporting the current shortfall until these new recruits have passed their tests."

https://www.bbc.co.uk/news/articles/clww81g52g1o