Bhavna - 1. No as the sale can be completed by your Father. If they protected the trust created by their 50% split be registering a form A restriction, then the transfer (sale/purchase) can be completed - see
PG 21 section 6 for guidance on how that may be done. Please do speak to the conveyancer acting on the sale to confirm
As your parents both owned the property probate would not be needed for your late Mother in order to deal with the property. It does not form part of her estate although you may have required probate for other purposes.
2. Once sold the proceeds of sale can be divided as appropriate and according to the trust/will - that is not something we are involved in so if you are unsure on how to divide the proceeds of sale then please seek legal advice