I am with them at the moment, taking the last 3 exams next week. There were no hidden costs, You just pay the CAA for each exam you take currently £63. No school I know of has this included in the price
If you take the £999 package, you get 3 x 1 week brush up in house sessions, they are run once a month, on a rolling basis. So 1 month is stage 1, next stage, ect, ect. Only online access is included, if you want the physical books, they can be bought for £500 from CATs. Most people find the online perfect. But others feel more comfortable studying the old fashion way.
Does not matter where you go to do the theory, you get to take the same exams as everyone else. So why pay anymore than you should. Use the extra money for private tutor, extra books, but I doubt you will need it, I'm spending mine on some extra hours flying