Having been dithering for ages whether the time is right for us to start fostering, I've made that initial call to the LA and we're booked into an introductory session next month 
. The lady I spoke to was really helpful and said DH being main carer is fine & that they don't have any restrictions on ages of birth children (ours are 2&5). It may still be that we hold off until DS2 starts school but I'm very excited that we've actually made a tentative start on our fostering journey.
Hope to be back on this board before too long.
LCN