Thanks for your question - I am Sam and I am one of the UK tax experts here on Just Answer.
Yes you will as you have another property already and adding you to the current deeds will not change that factor.
The only way to get around this is that husband makes new purchase in his sole name.
Let me know if I can assist further
I can reply to the stamp duty question but as the capital gain question is a new topic - I will need to send an additional services request (which will incur an additional cost)
So for the stamp duty - no you will not get a refund is you sell the flat within 3 years.as it is not your main residence up to the time the new purcahse was made and therefore are not replacing this sale with a new main residence.
Let me know if you wish to proceed with the capital gain question and I can send an additional services request.