I charge the same hourly rate for Maths and Further Maths. Tuition of larger groups is at a lower rate per student:
one-one tuition: £55
groups of two: £45 each
groups of three: £40 each
groups of four: £35 each
Some tutors do offer lower rates, but the tutors involved are sometimes not qualified teachers or are simply university students earning a bit of extra cash in their spare time. For a quality teaching experience you will usually have to pay a little more.
The fee doesn't just cover the hour of tuition, it also covers the time taken to prepare lessons, plan the course and create and source resources.
I ask for payment to be made in batches of 5 or 10 sessions, due before each batch starts. This can be made via BACS or Paypal. Details will be given when arranging the lessons. If you wish to have a trial lesson, then a single lesson can be booked for this purpose.