I’d assume the company you work for will sort out what you need in the way of docs, but here goes from memory.
V5 registration document or VE103 if it’s a hired or leased vehicle.
Insurance certificate
Test certificate
Official copy of community authorisation, blue certificate
CMR’s
Border check form for returning to the UK.
Driving licence
DCPC card
Equipment
Hi-viz
Warning triangle, 2 in some places
First aid kit for some countries
Spare bulbs
Toll box, compulsory for Belgium, Austria, Norway, Poland
Euro vignette for The Netherlands, Luxembourg, Denmark, Sweden.
Toll collect for Germany, might have a toll box, but if not, can book your route at most service area in Germany and at services near the border at most neighbouring countries.
Nice to have a toll box that covers France, Spain and Portugal
Toll box, Via card or credit card or cash for Italian tolls.
Try get away from stopping at the services, although mostly better than the UK, most countries also do thier version of truckstops, such as Routiers in France or Autohofs in Germany, plenty of advice of nice places to stop on here and various apps also available.
Mostly parking is free at services and truckstops, but some might charge, but that it refunded if you buy a meal.