Depends on how they implement it. If it’s flat £231 per week while retaining all other benefits, then yes, it would cost more.
If it’s £231, but that’s it, then no. It’ll cost less, and people would potentially lose out on a lot of stuff (council tax reduction, help with water, energy etc). It’s more akin to a “basic income scheme”.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.