Congrats!That may be a door for LBA income.
160 pounds for a day shooting looks like a fair price given your status with them. If that has been sugested accept it. 70-80 pounds if you're doing it to get your name out there looks fine too...it may get you more litle jobs if people see it's cheap, while you build up your experience and equipment.
I'm just trying to do the same thing...no luck so far...well kind of, got this thing going, a fashion shoot and i'll get a lens as payment (maybe the Tamron 28-75 f2,8...or if i get to save the money i may try to get a used 50-135 f2,8..).
After the shooting tell us how it went