When you enter the UK with goods you bought abroad, you don't need to pay any UK tax or duty if you transport them yourself, provided the goods are for your personal use or you've bought them as a gift for someone else.
There is however a limit to how much you can bring. This limit is known as a personal allowance. The level of personal allowance differs depending on whether you're arriving in England, Wales and Scotland, or Northern Ireland.
It is important to check the personal allowance for the different categories of goods before you enter the UK. If you exceed that allowance, you will have to pay import VAT, customs duty and excise duty, where applicable, on all the goods in that category, not just on the amount that's above the limit.
If the goods you bring with you exceed the personal allowance, you must either declare this and pay online before you travel or you must declare your goods at the border when you arrive.
You can check the personal allowance for tobacco, alcohol and other goods online.
Whether you'll be limited to a personal allowance for goods you take into Northern Ireland depends on where you're arriving from:
There is no limit on the amount of alcohol or tobacco or other goods you may bring into Northern Ireland. You may however be subjected to a customs check at the border if the amount of goods you arrive with gives the impression that you plan to sell the goods instead of keeping them for your personal use.
You can check the personal allowance for tobacco, alcohol and other goods online.