I would probably make more of these decisions after you take your CBT, but have no fear, a 125 will be tons of fun in the short-term.
Love mine, although it’s a scooter 😉 *beep beep*
Whatever you get, make sure it’s reliable. You don’t want to be worrying that it’s going to break down on you.
During my CBT, the Honda 125 I was on felt a bit poo – the gears weren’t that easy to get and it took a while to start 🙂
About helmets, don’t buy second hand (well I wouldn’t). Most people say if a helmet is dropped, it needs replacing – with second hand stuff you can’t trust that it’s not damaged – besides, you have try it on for size 🙂