In order to get a Sure Start Grant, you need to be on income support, income-based Job Seeker's allowance, disability element of Working Tax Credit (cut off for getting this at all is an annual combined income of about £14,000), or above the family element of Child Tax Credit. This is very clear on the application, so if you are not in receipt of and have qualified for one of these benefits, it doesn't make much sense to apply. You must also apply on or before your child is 3 months old.
When you apply for ANY benefit, your income will be taken into consideration as a couple.
Again, if your JOINT income is about the approximately £14,000 mark, don't count on getting Working Tax Credits. Child Tax Credits, yes, and again the amount will depend on your total income as a couple AND whether or not you use a registered child minder for childcare.
Based on your joint income, if you are a renter ONLY, you may or may not qualify for housing benefit. Check w/your local council about this. Some councils pay it directly to the landlord, others award it to the tenant to use on their rent. Housing Benefit applications are usually joint applications with Council Tax Benefit, but the only folks I've heard getting Council Tax Benefit are on income support or JSA.
Your Child Benefit award will be greater for the first year of your child's life, but expect it to drop rather sharply once your child turns one.