In England and Wales, enforcement agents are employed by your creditors to collect a debt. There are certain things you can do, such as contacting the enforcement agent or creditor directly to discuss payment of the debt and by not letting the enforcement agent into your home (though this is dependent on the debt type).
If an enforcement agent enters your home, they will write a list of what items can be removed for sale- this is called taking control of goods. To avoid the enforcement agent removing the goods you would need to repay the debt in full or set up a payment plan with the enforcement agent as part of a Controlled Goods Agreement (CGA). If this agreement is then broken then the Enforcement Agent can return to remove the goods. Controlled Goods Agreements are only applicable in England and Wales (see more information on dealing with enforcement agents).
In Scotland, enforcement agents are called Sheriff Officers. Sheriff Officers can only enter your home if they have the correct authority and permission to do so with a warrant. Unfortunately, if they have permission they can use necessary reasonable force to enter your home which may mean forcing open a door or breaking a window if you don’t let them in. If there is an Exceptional Attachment Order in place, the sheriff can enter your home to seize possessions that can be used to pay off your debts. There’s more Scotland specific advice here.
In Northern Ireland, court judgments are dealt with and enforced by the Enforcement of Judgments Office (EJO), a centralised unit whose powers and procedures are set out in legislation. There’s more Northern Ireland specific information here.
However, the most important thing is to address your debt as soon as you can. If you ignore things, they will continue to get worse.