Kell, you are being invited to the police station where you will be formally interviewed under caution etc. At the police station you will informed of certain legal rights which includes the right to legal representation. I would strongly suggest you consider the use of a solicitor which I understand is still free of charge (make sure you find out first) and ask for the solicitor to attend any formal interviews.
This allegation falls within the catagory of Domestic Violence and has a 'positive action' policy so it will be pursued. If you deny the allegations and the matter can not be locally resolved then a report is likely to be submitted to the Crown Prosecution Service for a decision which could take a few weeks depending on how busy the police are.
This is a summary answer, any questions pls ask.