Yes you can use it on Dogs but not advantage 40 as this is for cats. It costs anything from £7 - £15 for a pk of 3 or 4.

Have a look at this website, im not sure whether you will need a perscription for it but just have a look around the web

Advantage 40 (for small cat/dog/rabbit under 4kg) pack of 4 POM-Hyperdrug