Get to your Spanish course by plane
Ryanair and Monarch Airlines (low-cost airlines) fly regularly to Granada airport. There are also daily flights to/from Madrid and Barcelona, and from there to all major international airports.
You can also fly to/from Malaga and Almeria airports (EasyJet, Hapagfly, Ryanair, AirBerlin, Vueling, Helvetic, Flybe, etc.). Malaga and Almeria are only one hour and 45 minutes from Granada by bus. They are bigger airports so are connected with the most important international airports. For further information see Flights to Granada.
Driving to Granada
Along the coast, from Barcelona, you can take the AP7 motorway (with toll) to Alicante and then the A-92 motorway (free) to Granada. From Madrid take the A-4 motorway to Jaén, and then to Granada.
From/via Madrid is the best train route to Granada.
There are some International Coach Services that serve Granada (e.g. SAIA, Mundial). Please check the International Coach Services in your city.
If you are travelling within Spain there are national buses that have daily services to Granada. For example there are scheduled buses (every hour) to Granada from Barcelona, Madrid, Malaga and Almería. Alsina Graells is the most popular bus company in Andalucia and has many routes to/from Granada. National companies like Alsa also travel to/from Granada daily. You can find timetables on their websites.