I am totally with you on this issue, it really sucks and its just going to be us lower earners who miss out.
But, this is the exact reason why I gave up my job of 12 years two months ago, and my husband and I both feel like it was the best decision for our family. I have no advice, but unless you really need the money that you will be clearing each month, its just not worth working if you have two kids imo!!! I would only have been taking home about £200 a month, and it wasn't worth the 45 minute commute in traffic, the rushing around to make deadlines and the extra childcare.
Lucky for me I have a few friends who are SAHM's and we do get together alot and go to lots of sure start centres and babygroups, so I am pretty busy.
GOod luck!!!
(she says typing this on the sofa while her toddler daughter is watching CBeebies!!)