Another vote for GTS
I found them very professional with excellent study guides, helpful telephone/e-mail support and brilliant groundschool.
I am the wrong side of 50 years,have a full time job, and managed to complete the 3 modules with first time passes in all subjects - do not underestimate the amount of studying required. GTS will not enter you for an exam unless you have an adequate score in their mock papers.
Think very carefully about taking CPL writtens - it will limit your options compared to taking the ATPL exams - I understand that there is not a lot of extra work involved.
PM me for any further infomation