Do Terminal Loss relief and Closing year Rule go hand in hand because from what I know closing year rule might involve last two periods also although terminal loss relief involves last 12 months only
They are two separate exercises! The closing year rules would compute the actual loss arising in the tax years which could then be set against the total income of the current and / or preceding tax years whereas the terminal loss relief is as you say a separate calculation incorporating only the loss sustained in the last 12 months of trading and which is then able to be set off against the trading profits of the preceding 3 tax years