It's not alarming, but it is a sign of dehydration. You can call 111 for advice and offer plenty of fluids (breastmilk, formula of whatever your baby normally drinks) during the day.
Thank you all! He’s woke up again and had a big wee! 🙌🏽
I would contact them just to be safe. Does your baby’s soft spot look like it’s dipped inwards on their head? This can also be a sign to show if they are dehydrated. I’m sure everything is fine, but worth getting reassurance from medical professionals.