I can confirm that 2 x 30 mins a day for a standard poodle (the other pedigree dog used in this cross) can survive on this walk regime but only if at least the same amount of time is also give to mental stimulation and training. They are an extremely intelligent breed who can think for themselves, throw into that the working mind of a labrador or GR you are looking at a very clever dog who needs stimulation a lot of the day. I can also confirm that SPs takes at least four years to calm down, they are a bouncy in your face knock your kids over type of dog, ours bounce over the furniture like the wall of death. This of course is what we love about the breed, we've had them for years and know what to expect but to a novice owner it can all be very overwhelming. They are natural clowns and even with training will get themselves into lots of mischief.
What also concerns me about dog ownership these days, so many people go on looks, ah that looks cute, love the curly coat etc. Most doodles will require professional grooming every 8 weeks or so, at a cost of around £50 the nice pictures online are usually of very well groomed dogs, they don't look that nice all on their own. The less hairy variety, the ones that won't require as much clipper and scissor work are the shedding ones, they take after the lab or GR coat, so instead of leaving the hair with the groomer you will hoover it and wear it 24/7. If you think you want your dog to look 'natural' then you must be prepared for hours of brushing, dematting and combing, again they don't even look natural without lots of work, if you don't do this they will matt like crazy and matting hurts.
Asking the breeder isn't going to help you at all, they will be wanting you to buy a puppy and tell you what you want to hear, unless they are a truely good breeder concerned about where their puppies go, lifetime support etc then if they think it's not what you want will tell you so. Please don't look at the puppies if you are unsure, that's a sure fire way of letting your heart rule your head.
There will be lots of people who love their doodles, and why not, if they knew what to expect and have put in the work then that is the best possible outcome but you do want people to be honest with you.
Don't even consider a pup from untested parents, not health checked (that is entirely different, just a check from vet to say they look healthy) but tested, you want at least hips and eyes, elbows if possible and there are a few diseases in SPs Addisons (can't be tested for) & sebaceous adenitis which you will avoid carriers and affected dogs. I don't know of the labrador inherited diseases but you should research this. A cross breed will not necessarily be healthier, and could inherate diseases of either or both breeds, hip dysplasia is unfortunately common as usually both parents are not the best example of either breeds and unscored.
Think it over very carefully :)