If you bring in goods from France, or any EU country on which tax has been paid in that country, you do not have to pay any tax or duty on them in the UK. However any alcohol or tobacco you bring in must be for your own use and transported by you.
When returning to the United Kingdom from France, you should ensure that you adhere to the HMRC custom allowances. If you have goods in excess of the limits stated here then you must be able to prove to Customs Officials that the goods are for personal use only and not for commercial purposes
Guideline amounts are published by HMRC, and as follows:
Please note that these guidelines are subject to change. Before travelling you should ensure you have familiarised yourself with the guidelines at HMRC
If you have in excess of these limits, Customs Officials may ask questions regarding the items you have brought and how often you travel. If they believe that the goods are for a commercial purpose, they may be seized along with the vehicle used to transport them in, and may not be returned to you.