The Tiger Club does not have any restrictions on tailwheel hours for flying the Tiger Moth solo.
The Club does suggest that people should start on the SuperCub if they have not flown tailwheel aircraft before, as they will find this both easier and cheaper to learn. If someone wants to go straight onto the Tiger then that is OK.
The number of hours required depends on how the pilot handles the aircraft, some pilots with no tailwheel experience take five hours training, others more. Whatever it is a lot of fun!