[magnuz]

The top part of the cam cover should come off fairly easy.. you may be able to still see the part number on the belt if you can rotate the engine by hand. The supplier should be able to cross reference any part numbers ?

No special tools are needed, & you don't even need to remove the crank pulley, as there is enough clearance to get it past, by carefully twisting the belt & feeding it in, after you've removed the plastic bottom shield.
It's also probably a good idea to put extra marks on the pulleys before you start ?

You can also check the water pump for play,roughness, leaks, etc, but if it's the original volvo pump. it's unlikely to need replacing as they are excellent quality ?