July Books 8) Turlough and the Earthlink Dilemma, by Tony Attwood
It's not surprising that the "Companions of Doctor Who" series of books was dropped; if anything it's more surprising that another two were published (Harry Sullivan's War by Ian Marter and Terence Dudley's novelisation of K9 and Company) after this very unimpressive start. The evil female leader's name is Rehctaht, which probably tells you all you need to know. The plot, such as it is, has Turlough, back on his home planet, reinventing the Tardis and trying to prevent nuclear destruction. There is much confusion of timelines, and too much material hastily thrown together. I think there are about three different novels in here, but it is difficult to tell if any of them would have been any good.