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.
Newcastleton
Newcastleton, is a village in the Scottish Borders, a few miles from the border with England, on the Liddel Water. It is the site of Hermitage Castle. Newcastleton is 10 mi (16 km) eastern of Langholm, 17 mi (27 kilometres) south of Hawick, 24 mi (39 kilometres) north of Carlisle as well as 74 mi (119 kilometres) south of Edinburgh. Newcastleton was constructed as a result of the land clearances in the 1790s when people were forced to move from Old Castleton town. There has been a people event at Newcastleton given that 1970. "Copshaw Holm" (one more name for the village) is celebrated in the track "Copshawholm Fair", composed by David Anderson in 1830, as sung by Willie Scott to name a few.