This situation is quite hard to give a concrete answer on as there is an awful lot of information missing that could prove critical in dealing with this scenario.
Firstly how long was the worker in question actually working for you? You mention that she worked two hours a day up to two times a week, and depending on how long the period of time she has been doing these hours she would be defined as an ‘employee’ in the eyes of the law (irrespective of whether she has a written contract or not). With this in mind, any employee has rights which employers have to respect.
Secondly, if she is asking for a P45, I take it she has now left your employment? As such, why did she leave? If it was over a contentious issue then you may have some concerns about a tribunal claim. However, if she has resigned and you have had a clean break from her and she is merely asking for the P45 to start a new job then issue the P45 and sweep this episode under the rug, and in that case you will also get your property back – if she is true to her word. Otherwise, you could find it difficult to deduct any wages you feel you are owed, in place of the company property she has, due to the lack of any written contract in place.
Overall, you need to approach this with caution; you don’t want to risk a tribunal claim being made against you. You need to be confident that you can prove she has left your employment of her own accord and with no wrong doing on your behalf.