If you are new to the import process the following check list will provide you with a rough guide to what you need to do:
You need an EORI number that starts with GB to import goods into England, Wales or Scotland. You will need a new one if you have an EORI that does not start with GB.
The business sending you the goods may need to make an export declaration in their country or secure licences or certificates to send goods to the UK.
You can hire someone to deal with customs and transport the goods for you, or you can do it yourself. Most businesses that import goods use a transporter or customs agent.
If the UK has a trade agreement with the country you are importing from, you may be able to pay less duty or no duty on the goods (known as a 'preferential rate').
If you have appointed someone to deal with UK customs for you, they will make the declaration and get your goods through the UK border.
Unless you have experience dealing with cross-border transactions appointing a customs agent or similar organisation would seem to be a sensible option unless the value and frequency of imports is unlikely to be significant.
More detailed information is available free of charge on the GOV.UK website.