Yes it does. You won't need a grant of probate to sell the property, your dad can still sell the property with you acting as his attorney, but you will need to appoint a second trustee if you are the sole attorney. This is not as complicated as it sounds, and can be done in the deed that transfers the property to the buyers. It might be an idea to appoint your brother, but it could be anyone.
Strictly speaking you should take out a grant of probate to deal with your mum's share of the proceeds of sale, but this won't be required for the mechanics of the sale of the property.
The solicitors acting on the sale of the house should be able to give you appropriate legal advice.