Skodaoctavia16

Hello I have a 2014 Skoda Octavia 1.6 diesel. This past weekend after a decent motorway drive I got a coolant low red message on dash. Waiting for it to cool at filled the expansion tank, on Saturday. By Monday it was at minimum and had a small coolant puddle on the floor by driver's door . Filled again and drove another motorway drive. Coolant level remained steady, and temperature didn't exceed optimal for the entire drive. The car is on 122k and has minimal paperwork prior to me buying this one owner car. It has had a new radiator and expansion/overflow tub replacement in November of 2020. And I've had no issues till this past weekend. I've drove nearly 350miles and topped up about 600ml if coolant,which is now at max level. Today it was at the garage and has passed pressure tests. They've had a look and can't find a leak. Without tearing the car to peices. Questions Is it worth booking it in for water pump and cambelt replacement as I've no knowledge if it being done ? Car was serviced a week before this happened,oil looked good no coolant or water in engine . Garage I took it to today said to just monitor as these issues will get worse. I know it could be many things but water pumps are common. What would you guys do and what's the average cost of a pump and belt