Universal credit doesn't affect "us" being immigrants who do not have access to benefits.
The only immigrants who
can't claim any public funds, are those who come here on the work visas and their dependant, those on the Ancestry visa and their dependant and the others on the points based visa and their dependant.
Not all benefits are Public Funds and these immigrants can claim these benefits.
Some of those that have "no recourse to public funds" can claim benefits through their British citizen or ILR spouse.e.g. Working Tax Credits, Child Tax Credit (and I sassume their replacement UC) Child Beneift, and their spouse can claim Housing benefit too and they can live in that property. The difference in the rate for HB between a couple with a child and a single parent with a child where the spouse can't claim, is zero.
Those EEA citizens who are in work (at present, even if only part-time or they are self employed and avoid paying Income Tax and pay a lower amount on their NIC;) can claim benefits as can their non-EEA citizen Family Members.