It's very unlikely that you'll find another school that does exactly the same exam boards and topics as your school. They may also be teaching things in a different order.
It's extremely inadvisable - if you can possibly avoid changing schools, you should. It could have a very detrimental effect on your A-level grades.
In addition to the points above, if you are going to be applying to univerity, your teachers will have very little time to get to know you before doing your reference. I would therefore also advise against changing schools if possible.