Some quick thoughts.
Availabilty and quality of aircraft and instructors.
Number of days you can fly per week ,some including where I learned do weekends or four days only etc.
You can be looking at up to £165 per hour.
You need books,best to buy a complete set ,up to date editions
You need equipment,you can use club headset but I prefered to have my own.
You need to feel at ease with where you are learning,for me that was more important than saving a few hundred pounds.
Also wants to be local so you can be there if weather conditions change.
You will find that most schools will not do more than two lessons a day because of student overload.
Good luck.
Lister