PootlewasthebestFlump try not to worry... I'm not a massive fan of Ofsted either!
As your future child/ren will have been in care you will get priority of whichever school you want them to go. However, if the local authority have these rules about the type of school that the child will go to then they may decide to dictate which school that is, or what selection of school this can be while the child is in their care. This is not something I have heard of before.
I would GUESS:
If the child is not yet school age, don't worry, once adopted social services will not be able to tell you where to send your child.
If the child is school-age already or just about to start school you may want to look at all the possible local schools with the child in mind. EG are they into music, are they into art/drama/sport etc and which local school may match their interests best.
Once you have looked at all the local options make a decision based on what you think is really best for the child you will be parenting and then talk to the social worker about what seems to be the case and what they recommend.
I would say your social worker may well know very little about the child but the child's social worker may know more, if you can persuade their social worker (or your social worker) that a certain school is better then you may have a chance, but if it is rule, you may have to go along with it.
Please bear in mind that schools can change and it may well be that the lovely local schools gets 'better' in the eyes of Ofsted, or that another falls from glory!
Be aware also that small schools are not always best for adopted children. Being very close to your house may or may not be great, it could go either way. It may also be that the other schools which Osted approves of in the area are actually quite good.
Re I had wanted our future child to go here not just because of its ethos but because I felt going to the local school was important for integration etc. Just be careful about the assumption that what you had thought about a 'mythical' future child may not be best for a real life future child - it might be, it might not be. If you appear very rigid on this you can expect the social workers to maybe feel a bit defensive of their rules or whatever. However, if you come across as open and exploring then you may find they end up agreeing with you if this local school really would be best for your new child.
Finally, once your child is adopted if they are not happy at the local school you take them to or if they are not thriving there then if it is not working out for the child you can move them. Early in school careers the moving about is not such a big issue but as they get older it will be more important for them to find a suitable school and build a group of friends etc., IMHO. So it really does depend if we are talking about 4 or 5 or 8 or 9 or 13!! etc. I would say the older they are the more important it is to try not to make too many moved but if a school is not working and a child is not happy etc then moving is a choice, and once the child is legally in your care it will be your choice.