Taxis are available for getting around larger towns, however they  may be hard to find at times. If you are out in a more rural area, away from the larger cities there may not be any taxi service available. Also, be careful when venturing into areas where there is limited cellular service, mountainous regions for example, because you may not be able to call for a taxi to bring you back. Make sure you have the phone number of the taxi service with you when it drops you off so that if the internet is poor you can still call them to pick you up.

There are some ride sharing apps that operate in Europe. Check which ones work in the area you will be in.  Not all of the ones that operate in North America are prevalent in Europe. 

One last thought on the availability of taxis and rideshare drivers. Some holidays and certain times of the day you may experience limited service. We were stuck at Stonehenge once the little towns in the are were not big enough to have a taxi and all of the rideshare drivers were engaged taking kids to school.