Hi MarkSteed,
You should submit a form 17 with a valid declaration of trust stating the percentage split.
This should be signed by both yourself and your wife. See TSEM 9230
TSEM9230 - Ownership and income tax: legal background: joint ownership - presumption of joint tenancy.
Relief on interest from a mortgage can only be made by the person who takes out the loan, pays the interest on the loan and applies from the loan in a form that meets the qualifying conditions.
This is explained in the savings and investments manual SAIM10030
SAIM10030 - Relief for interest paid: general conditions: the claimant.
There is no capital gain when a property is transferred between husband and wife.
This is at a no gain/no loss stance. See CG22070.
CG22070 - Transfer of assets between spouses: definitions.
Regarding stamp duty please call 0300 200 3510.
Thank you.