You should pull up and remove weeds by hand as and when they appear. If it is a regular problem, you might need to reseal the paving. In extreme cases, the sub layer itself may need to be re-laid. You can use weed killer, however some paving can be discoloured by stronger weed killers.
Workington
Workington is a town, civil parish and port around the west seacoast of Cumbria, England, at the mouth of the River Derwent. Historically in Cumberland and lying within the Borough of Allerdale, Workington is 32 miles (51.5 km) south west of Carlisle, 7 miles (11.3 km) west of Cockermouth, and 5 miles (8.0 km) southwest of Maryport. It features a population of 25,207.