London is a big city. If you check online you can easily find multiple places to learn Spanish. However we would strongly advise you not to choose tutoring agencies that focus in all subjects like maths, science etc. Those sites basically any person can be advertised there so there is no filter regarding the quality of the tutors there. The profiles are uploaded by a computer system so no one can guarantee you that the person is a certified Spanish teacher.
For this reason we recommend you to select only companies that specialise specifically in teaching Spanish. It can be a Spanish school that teaches group lessons or a company like Spanish Tutors London that focuses on Spanish tutoring services exclusively
Both options have its advantages and inconveniences. Learning Spanish in a group is a good way to socialise, make friends and meet like minded people. However group classes are not as effective as private lessons if you want to learn fast. One reason is because in the group classes the teacher has to help everyone and respond to questions that every student has. The progress of the class will be slowed down because of that. Another reason is because the hardest part to improve is speaking, and you can only improve your speaking skills via direct interaction with your teacher. So if you want to learn fast the best option is that you get a Spanish private tutor. They will be able to guide you into your new language at the speed that you need and make sure that you keep progressing smoothly.