Forced marriage is illegal in the UK. According to the Crown Prosecution Service, someone can be regarded as having committed this offence if they: 

“Intentionally force a person to enter into marriage, believing the person does not consent, takes steps to cause a person whom they know cannot consent to marriage to enter marriage, deceives someone into going abroad for the specific purpose of forcing them to marry. An offence is committed whether or not the Forced Marriage goes ahead” 
The maximum penalty for the offence of forced marriage is seven years in prison.  

Under UK law, a marriage can be considered ‘voidable’ under certain circumstances. A ‘void’ marriage is one that is not legally valid. One of the reasons a marriage may be void, is because there was a lack of consent by one or both parties. In cases such as this, you may be able to get a marriage annulled. Annulment is different to divorce as it can be applied for in the first year of marriage and unlike divorce, it identifies the marriage was never legitimate and so you regain the status of ‘never married’. 

Where religious marriages are concerned, these are not recognised in English law unless the civil content and requirements are met. Where they aren’t met, the law would treat you as unmarried and living with a partner.  
If a marriage takes place abroad, this becomes a little more complicated and depends on whether the marriage is legally recognised in the country it took place and if each party has capacity under the laws of the country they recognise as their main permanent home. It is advisable to get legal advice if you have been married abroad and are unsure if your marriage is legally recognised.