CGT on sale of shares from a US ESPP

My husband works for the US company Labcorp Holdings Inc and has joined the Employee Share Purchase Plan (ESPP). He has completed a W8-BEN form and I believe that the scheme withholds when shares are purchased every six months. Please can you confirm that the only additional tax to pay would be potential CGT when the shares are sold (is over £3k profit) providing they are a qualifying disposal. Thanks

Hi ,
 

CGT would only be due if having sold the Shares the overall Gain exceeded the Annual Exemption of £3,000.   Thank you .