No court will allow non-payment of child maintenance to be a factor in a divorce financial settlement because you will always be entitled and eligible to claim it. You could agree and then a month later put a claim in, and he would have to pay. So child maintenance is irrelevant and can’t be factored in.
As an aside though I don’t know why you’d want to agree not to claim child maintenance, your children are young. Not to be negative but absolutely anything could happen, cost of living is only going up, you’d be stretching yourself on the house if you could only “just about” get the mortgage in your own name, can you afford to be the only one feeding, clothing, housing, paying for every single thing for those children? School uniforms, birthday and christmas presents, parties, food, school trips, clothes and shoes, as they get older that will become 2 mobile phones & phone contracts, 2 sets of driving lessons potentially, on top of being completely financially responsible for the upkeep of the house? Even in the best maintained homes things come up unexpectedly, burst pipe, a leak, boiler breaks down, oven breaks, bills going up, with only 1 income to sort all of that out plus support 3 people?
And that’s not factoring in that anything can happen health & job wise, you could find yourself falling unwell and unable to work full time ever again, you’d still be the only one supporting your household and children, it’s just not realistic to think that not claiming any child maintenance is a sensible option.