RTP is probably your best way, though it's not as widely offered as GTP. You need to get in touch with your local EBITT and find out. You can do RTP at any school in England, and there are some funded places by TDA. Otherwise a school has to find money for your training and salary. See http://www.tda.gov.uk/get-into-teaching/teacher-training-options/registered-teacher-programme.aspx and look for your local EBITT provider in the search section of TDA site.