If the paint is water based then use very hot water and soap and will come off quick.
If its solvent / oil based use a paint thinner or acetone let it soak for 15 min.
Uni bond (use 1 part unibond and 3 parts water) the wall and that will seal it in.
Fill and sand any holes and go for it. Dont worry a out the old paint. Just scrape off any loose stuff but it's not important.
Emulsion over the top. With 3 to 4 coats
Use primer paints on wood work only.
Number 1 don't go travis perkins they are expensive. Go to howdens.
Need to check the width of the frame
They come in nominal sizes 4¼",5¼,6¼ etc
And ask for a fire check frame. Loose stops are the easiest to fit because you can hide the screws with the loose stops.
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