DIY guide for plastering - where?

Have a read through this:

I've just done the very same thing. Finding the thicker ceiling board was a problem. My old ceiling measured 14mm. The best fit I could find was 12mm.

Fitting the board is no problem. Use plasterboard screws rather than nails - the banging can cause more damage. I did not tape the edges but used plasterboard sealant, which did a nice job.

In retrospect I think I should have tried putting on a skim to get a closer match of thicknesses first. I thought, wrongly the Artex finish would bring it up to the right thickness - you can see it did not!

Getting an Artex pattern match is not easy. With mine (probably the most common) I had to use a (homemade) wooden float with a sponge layer all wrapped in cling film. The suction produces an irregular crest effect.

It is a very messy job, particularly if you sand it back later to have another go.