I have a black Lab cross who is to all intents and purposes a Lab with a slightly thinner face and less of a tendency to perform the walking dustbin routine than the stereotypical Lab.
Oh... and he's also not fond of young children and if I were ever to need to rehome him, heaven forbid, I wouldn't dream of letting you adopt him therefore. My younger German Shepherd, on the other hand, adores kids. You'd all love him, I'm sure.
What I'm saying is that there is no such thing as X breed being better than Y breed - it's down to the individual dog. If a Lab's the breed you want, great, go for it, but I'd recommend that you approach rescue with an open mind and you might be surprised and find a... oh, I don't know... Boxer, Jack Russell or crossbreed who is just perfect for you and your family. I see that happening quite a lot in rescue and have done the same myself - went looking for a young little collie cross girl but the dog which I adopted and which was perfect for us was a 9 year old ruddy great long haired white German Shepherd! Best decision I ever made!
But, if you want Lab facts, I'll try, going on my boy.
Insurance - nearly £15 per month for a policy which doesn't restrict to just a years treatment. (He's around-about 11 years old).
Food - I feed kibble mixed with Naturediet, mince, tripe or an additive free canned food. The kibble isn't cheap at £49 a 15kg sack (Fish4Dogs, additive free) but it's worth it. Hard to say how long it lasts as I also have 2 other large dogs! That would last my Lab about 5 or 6 weeks
Jabs - Vary greatly according to where you live and which vet you go to, would recommend that you ring around. DO NOT touch a rescue which sends dogs out unvaccinated unless there is good medical reason why he should not be vaxed. Likewise avoid those which do not neuter before rehoming, don't homecheck and don't guarantee to take the dog back at ANY point in his life if you can't keep him.
Many of the bigger rescues have blanket policies about not rehoming to families with young DC so approach breed rescue and the smaller independent no-kill rescues as they are more likely to decide on a case by case basis and not have a one size fits all policy.
HTH. :)