There is nothing legally to prevent you wearing your late father's medals, but I would advise against you doing so.
The medals were given to your father in recognition of the services HE gave to his nation and if you wore them, it could give the appearance that somehow, you were trying to create the illusion that you won them. There was a story recently of a man who wore lots of medals to the remembrance ceremony at the Cenotaph. A neighbour recognised him, told a newspaper, and he was then widely ridiculed. He'd never been anywhere near a war and had bought the medals on ebay.
So you can wear them if you want to, but you might upset a few people.