The majority of your running will probably be done outdoors, however, if you do have access to a treadmill it is a perfectly viable option to get in some quality training. But like with all your training having a focus and structure to your workout will be beneficial.
Why not mix it up and incorporate some strength and conditioning exercises and get a circuit workout going. For example, 5 mins running, 15 lunges each leg, 5 mins running, 30 squats and so on.
Be sure to use a 1% gradient on the treadmill when not doing efforts at other gradients, as it is more like running outdoors. Also, beware because the treadmill is such a perfectly flat surface only running on a this won’t develop much lateral control (that is any sideways motion, and your body’s ability to control and minimise it) in your running, head outdoors and run off-road to help develop lateral control on movement in your running.
Another downside to the treadmill is your ability to learn and understand pacing because you are manually adjusting the pace normally at set intervals you don’t learn to fully understand the pace you are naturally able to hold for a longer period of time.
Running is a brilliant outdoor sport, make sure you keep some variety to your outdoor running, plan some different safe running routes, think about finding a group to run with there are a lot of running clubs throughout the UK that normally offer something for all abilities or just find a friend who’s keen on running and plan to meet them once a week.
Take a look at the structuring sessions section and don’t just head out for unfocused plodding miles all the time (it’s ok once in a while) incorporate hills, intervals off and on-road running.