Hi, to close my question off, I bought the following Thule parts which fit perfectly:
1 x Thule (252) Rapid System Fixpoint XT low feet (4) no. 753
1 x Thule Rapid Railing adapter kit no. 4058 (Volvo XC90 (2015 onwards) )
1 x Thule (88) Rapid System 127cm WingBars (2) no. 969
Incidently, if you buy these from
www.roofbox.co.uk they also have a lock matching service where they will give you locks that all have the same key. Very handy as I also bought 3 bike carriers and so could have ended up with 4 different keys for the 10 locks used!