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.
Cornhill-on-tweed
Cornhill-on-Tweed (population 347) is a little town as well as civil church in Northumberland, England regarding 1 mile (1.6 kilometres) to the east of Coldstream, Scotland. The districts of West Learmouth and also East Learmouth lie to the south and west of the town specifically. A mile north-west of the village, on a spur above the River Tweed are the earthwork continues to be of Cornhill Castle. Cornhill-on-Tweed exists at a junction of the A697 and also A698 roads - the latter linking to Berwick-upon-Tweed, the nearest significant community, some 13 miles (21 kilometres) away.