Hi Sarah - we can't confirm anything with regards what's needed to enable you to now deal with the property/estate as appropriate.
From a purely registration point of view if the property was registered in your Dad's name then we would need probate/letters of administration for him.
If there's a caveat/condition re the Letters of Administration then that can impact depending on what the limitation actually means. There are scenarios where a chain of representation can be created but again that's a probate/letters of administration point that you'd need legal/wider advice on
If you are looking for wider advice then you could try online forums such as Money Saving Expert but a legal rep familiar with probate/letters of administration would be best