As an alternate path, since you live in what is for the time being the United Kingdom, you can probably get Amazon Cars to sell you a set of their 140 fast road springs. They no longer ship these to North America because of 'liability' issues - so they say. These are progressive (actually look more like dual rate) fronts and single rate rears which have a ride height about 20-25 mm less than original (depending on how heavy your car is). The higher spring rate will inherently reduce body roll due to compression of the suspension and they are not a brutal spring like the Lesjofors that I had on my 140 previously.
I currently have the IPD front and back sway anti roll bars and with the Amazon Cars springs (I must have been the last person in North America that they would ship to) I am looking to ditch the IPD rear bar and move back to an original sized bar on the front (waiting for COVID 19 to abate so I can troll the junkyards looking for a donor 140). An 18 mm bar (if it was still available) might have been a nice option with slightly shorter & stiffer springs.
The comment in the Volvo catalogue 'Although understeer is increased with the use of the bar, many drivers find it "interesting"' is rather "interesting" - as in interesting good or interesting bad?. Personally, I now find the approach of correcting for a bunch of front understeer because of a big front anti sway bar by adding rear understeer with a rear anti sway bar odd.