You can remortgage when separated. If you have separated and you are still in contact with the ex-partner, then you will need their signature to remortgage with both of you on the property deeds. On the application of the mortgage, however, this may be a great time to consider taking them off of the mortgage and ownership of the property so you can remortgage and do a “Transfer of Equity” to remove your ex-partner. Still, they do need to sign documents and get their own legal advice on this matter.
If you have separated and you wish to take off your ex-partner, then you can still do this, but this will involve a “Transfer of Equity”. This transfers the equity into the sole name of the person remortgaging. The ex-partner and the person remortgaging will BOTH need to sign the Transfer of Equity TR1 form. There will be extra costs you will need to pay the solicitor for doing the “Transfer of Equity”. Solicitor's costs to do the “Transfer of Equity” can vary but they can range from £250 to £600 plus VAT approximately. Sometimes the mortgage company doing the remortgage that offers free legal services will not include the Transfer of Equity in this but only charge a few hundred pounds more for this extra service.