Tom - scraping, chemicals or pressure washing, take you pick. Scraping = wrist ache, back-breaking and only takes the 'tops off'; chemical = Path, Patio & Drive Cleaner (widely available, including the DIY sheds); pressure washer (hire or buy - if you've got a big area that'll need doing often then purchase a machine, £50 - £100). If you pressure wash then you'll have to re-dress the surface with new sand, brushed in.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local