I'm from Spain, originally, and my parents own a house there. I live in the UK permanently now and am UK tax resident. After my mother's passing, I inherited one-sixth of the house, but that value was never transferred to me - the house was to remain my father’s. He is now planning to sell the property to buy a smaller apartment. Will I need to pay tax on my share of the money, even though again - I will not receive it in anyway? 

Strictly speaking, yes. It seems to me that you inherited ownership of one-sixth of the house, but either your father had the right to live in it, or even if he didn't have the right, he did so anyway. Now that the house is being sold, if it is worth more than it was when your mother died, then you are making a capital gain. Being UK resident, you are liable to UK tax on your worldwide capital gains. If there is Spanish tax on this sale, most likely you will be eligible to double tax relief. As for not receiving any of the sale proceeds, I would imagine that you have a one-sixth share of the new apartment. Most likely this is an internal family matter that needs to be sorted out in a 'diplomatic' way.