It's worth posing both questions to them. From what I can gather Allsorts have a pretty high rehome rate for a small indpendent rescue (can be a bad thing, fast rehomes with limited previous knowledge and assessment can result in a high return rate BUT I don't know if this is the case here or not). Going on that it's possible that they neuter males but sometimes don't have bitches in long enough to know if they're spayed or not and they may therefore insist on spaying afterwards, so do ask.
Personally I would advocate that all rescues are spayed/neutered before rehoming - had I needed to consider their offer to take the dog I mentioned upthread I would have ensured this before placing him there or else sought someone else's help. This is of course unless they're pups - I don't hold with the policy which some RSPCA shelters hold of neutering pups at a ridiculously early age and there I would expect rescue to rehome with a contract insisting that the owner arranged neutering ASAP and that they followed up to ensure that this was carried out.
I would strongly urge you to avoid any rescue which does not neuter/spay routinely with these exceptions, they would not be being responsible, would be adding to the problems that rescue faces and I'd worry what else they were lax about.
Ask too about you having a 4 yo as they will home a (suitable) dog over 2 with children who are past pre-school age occasionally, when they feel that they have the right dog to offer and the family is suitable. Being an independent rescue they will be able to bend the rules if they think they can help, whereas someone like the RSPCA wouldn't be able to.
If you're in Kent I'd have a word with the Dog Warden for Dartford council. No, not about pound dogs, that's not a good idea, :) but he's a loony dedicated, no kill believing rescuer in his spare time and will be able to give you solid advice on Kent and surrounding rescues and rescuing in general. His name's Niall Lester - call him at the council or if you'd like to you'll find him on Facebook too.