Dorset LEP have valued the county’s tourism at £1bn per year and employing 40,000 people.
https://www.dorsetlep.co.uk/news-article/tourism-crucial-to-dorset-s-economic-recovery
The Visit Dorset website has a report that estimates the tourism employment to be 32k.
Visit Dorset 2018 Report (The Economic Impact of Dorset’s Visitor Economy)
I contacted Visit Britain to see whether from their statistics they had other reports to show the numbers going from county X to county Y. They said no.