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Quick update. First piece is up! I didn't bother with pasting the wall first and letting it dry but I have gently sanded the wall over, and it does feel lovely and smooth now. It's a new build so the walls and pretty smooth anyway, but thought I'd better follow some of the advise given! :-)
It's not a massive wall so not many pieces to go up. Having a quick brew now before tackling the next piece. Thanks for all the brilliant advice.