There is more information and guidance here Apprenticeships | Careers Wales (gov.wales).
These are the providers of construction related training in Wales:
Network75: Network75 | University of South Wales
Capital Training Ground Ltd: https://capital-training-south-wales-ltd.mytrainingwebsite.co.uk/
Cardiff and Vale College: https://www.cavc.ac.uk/en/16-18/apprenticeships/
Coleg Cambria: https://www.cambria.ac.uk/subject/apprenticeships/
Pembrokeshire College: https://www.pembrokeshire.ac.uk/