In order to get an injunction you will need to go before a Judge in the County Court. For details on how to apply, please see the link in 'Related Information' (You may wish to obtain advice and/or assistance from a solicitor but this is not a legal requirement). The Judge will hear the application and decide whether or not it is suitable to issue an injunction. At the first hearing the Judge will (more than likely) issue an interim order, followed by a further hearing to issue the injunction.
The average cost of obtaining an injunction is approximately £500. Legal aid is available for certain types of injunctions providing you meet the criteria but it is not available for defending against an injunction.
Injunctions under the Family Law Act as described above are not only available to ex partners, there is an extensive list of people classed as relatives and cohabitants. Co-habitants are couples who live together but are not married.
The National Centre for Domestic Violence can obtain injunctions for those suffering from domestic violence. For a link to this and other websites that can offer further guidance and support, please see 'Related Information' for further details.
You should report this behaviour to your local police force if either you or your solicitor feel that it amounts to a criminal offence. In these circumstances an injunction may also carry a power of arrest.