Mine sprung a leak from the rubber elbow that joins the metal filler pipe to the tank, its about 6" long and should be easy but for the fact it's obscured by subframe. I tried removing spring and shock but it was just a waste of time you'd need baby sized hands to get in there
You can see it from underneath with a torch and possibly do a very temporary repair with a bit of bike inner tube and a big jubilee clamp if you're really persistent
If that's the same for you then the filler part and breather (might as well do both) is about 50quid Inc delivery from scandix but probably need to add a few hours labour to drop subframe slightly to get at it
Part numbers
https://www.skandix.de/en/spare-part...-tank/1028301/
Probably available elsewhere as well try ebay
I had to use a normal garage because the specialist place was insisting on supplying the parts themselves no doubt at a big mark up. Not willing to use parts i supplied despite the fact it's in a bag with volvo written all over it