I teach children of all abilities and have experience entering pupils for both ABRSM and Trinity exams.  The exams are not compulsory and some children prefer to learn without that added pressure.  Others enjoy the sense of achievement they give and are more motivated when preparing an exam.  

Lessons can be any length of time, from 20 mins to an hour.  

If you don't already have a cello or are not sure whether to invest in one until you   become more accomplished, I can help you organise a rented instrument and         advise on which size may be suitable. Children will also need a suitable chair         that is low enough to allow the child's knees to bend at a 90 degree angle.

Here is an approximate guide for choosing the correct size of cello:
Ages 4-5 one eighth
Ages 5-7 one quarter
Ages 7-9 one half
Ages 9-11 three quarters
Ages 12+ full size.