I strongly advise against pulling the column! If the UJ doesn't loosen then you will over-extend the intermediate shaft and knacker the bearing in it.When @Umfaan helped me remove mine, the same issue to pull the column out of the UJ meant I had to cut off part of the end of my biggest ( longest) flat head screwdriver with an angle grinder so that the 'wedge' of the screwdriver head was already 3-4mm wide before it went into gap you are needing to open slightly. Being about a foot long handle, I could tap the end of the screwdriver from above the heatshield with a lump hammer and this opened up the gap enough to release the column from the UJ. Having two people also helped as one could pull from the cockpit while the other tapped open the UJ. Remember to mark both the column and the UJ before you pull them apart so you can see what orientation to put it back together or to put in your replacement one
Keep the column mounted solidly in the car and tap the UJ downwards.