A wooden planter can be a great way to start growing in an area where there is no or little soil or perhaps a weed issue. The planters will last a good few years if you line them with something to keep the soil off the wood. Old compost bags are great for this or a landscape fabric. Think about the size you can manage and the amount of compost or soil you will need to fill the planter. The wood can be expensive but there are often recycled wood organisations that will help. Dundee and Angus wood recycling may be able to help. https://www.facebook.com/DundeeandAngusWoodRecycling/.
Make sure the planters are a size you can manage in terms of access and stretching across them to tend the plants. Usually they should be no wider than 1.5 metres.
They need to be filled with a good quality growing material like screened top soil or compost or a mix of both. Many local authorities will have supplies of compost at the local recycling sites. Homemade compost is another great addition.
Further Reading: https://www.rhs.org.uk/garden-features/how-to-make-a-raised-bed
