Can't say I spend much time in cbeebies, it it looks like the bigger rides (get set go, postman pat, ITNGMBR, octanauts) get queues around half hour or more. Despite the fact next year's flat has a queue for nearly three hours worth of people, the smaller rides in cbeebies rarely get queues. Cbeebies is also open for ERT you can get there, as everything is walk on.
Also, after Thomas land I wouldn't get your hopes up about cbeebies
Also, after Thomas land I wouldn't get your hopes up about cbeebies