Skyblue
I did my ATR rating with Skyblue and was very happy with the whole experience. Their trainers and examiner were very experienced and professional and the cost was the best at the time.
Skyblue are a TRTO so they do not promise jobs or line training etc, etc. (unless things have changed recently). However, they are very well respected and also very well connected. This did help when getting an ATR job.
Have a look at their website or give them a call as that will give you the latest details, costs, etc