I don't recommend any fully faired motorcycle as a first bike. Dropping the bike in your first few months is a virtual innevitability IMO and fairings are really expensive to repair/replace. Everyone I've heard from who has dropped their TT600 has reported a four digit repair bill. Frame sliders would help, but the TT doesn't have a good place to mount sliders without drilling a big hole in the bodywork.
On the plus side, TT600 insurance is a lot cheaper than for Japanese 600s. Also, Triumph actually does offer a throttle restrictor for the TT600. It's in their accessory catalog as a 34PS kit and is available to meet tiered licensing restrictions in the UK. I don't recommend this kit, however. Just tell her not to go crazy with the throttle for a while.
-KeithU