There is a firm of harp makers in Godstone, Surrey who make excellent harps and may well be able to suggest someone. Write to Pilgrim Harps, Stanstead House, Tilburstow Hill Road, South Godstone, Surrey RH9 8NA; phone 0134-289-3242.
Or, PM me (or email me privately: I'm on the Harplist) because I know someone in Kent who might be able to do it - she's a lovely lady, the perfect person to have around on a happy occasion like a wedding. I haven't spoken to her in awhile, but will pass on a contact mailing address for her (I don't like to hand out private phone numbers and have no email for her). Best of luck!