I lived and worked in Amsterdam from 1997 thru 2001 as a Chippy, not Tiling then. Only one time I ever had a problem getting paid when the agent did not have the right paperwork working on a big site in Utrecht. Otherwise a great time.
At 42 I'm prob a little too old to go clubbing with you but I'd be grateful if you could pass on the name of the agency as I'm considering going back there myself.
If I can be of any more help then feel free to email me at
Phillf@hotmail.com
If I was you I'd go for it , however I would ask the agent where you are responsible to pay tax and insurance contributions, if you are liable to pay any in The Netherlands then it could prove to be a considerable chunk of your wage. If you are liable to pay in the UK then you might get away with not paying anything

Cheers,
Phil