If you are sure that you want to be just a flying instructor then you can take the 8 CPL rather than the 14 ATPL exams. However, if you later decide that you want to work as a commercial pilot outside of instructing you will need to go back and sit all 14 ATPL exams (you can get a CPL/IR by sitting the CPL exams and later the 7 IR exams but it is not the same as the ATPL set and will not enable you to get the frozen ATPL at the end of it).
Onle a few ground schools do the CPL distance learning: Atlantic Flight Training at Coventry, GTS at Bournemouth and I think the Cranfield College. I don't know of any others currently.