Gift holdover relief for CGT applies to 'business assets' (ie the land would have to be used by your father in his business). You really need to get proper advice from a solicitor (preferably one who is a member of the Society of Trust and Estate Practitioners 'STEP') as to whether this relief may apply in your case. The effect of claiming holdover relief is that there is no immediate charge to CGT, but your father's gain on the land is passed to you. So when you eventually sell the land, your gain is calculated by reference to the value of the land at the date your father acquired it. If you keep the land until you die, the gain is wiped out.
For inheritance tax, there are two possible reliefs - agricultural property relief and business property relief. These reliefs apply to lifetime gifts as well as on death.