Moving North from London admission help needed

[Blueundies]

We are in a common dilemma. Moving in spring from London to the NW. The school we would like (we have friends at etc) has a place for Year5 DC but not reception DC at the mo. The LA say they can't offer place until we move. However, if there is a space, can I apply via the London LA in year transfer and then move once we have the yr5 place? The school has an unfilled place at the mo and no wait list for year 5. We will be moved there within a few weeks.
I will then appeal for reception place or send to another local school until they can admit DC2.
Can anyone clarify this for me?
Alternately we will try and move asap and hope the year5 place is still free. Its a massively over subscribed school BTW.
Thanks

Can anyone help?

In theory you can apply via your current LA for the year 5 place using your current address and if the place is still open then the school has to give you the place. The question that will come back is when is the place going to be taken up, because most LA / schools like the place to be filled within a few weeks. They may well be looking for the DC in year 5 to start after half term and you really need to be saying to them he will start as soon as place is accepted. Under those criteria it might just be best to apply direct to the school and say they will start the week after they offer the place and see what happens.
The reception place is more difficult. Many schools will have admission numbers around classes of 30 and any appeal for that year group will be an infant class size regs appeal. You can only win such an appeal either because a mistake was made - not at all likely given it is an in-year application or the decision not to admit is completely unreasonable - for that read perverse and that again is unlikely. It is therefore probable that the only way you are going to get a place in reception is when somebody leaves and you are top of the waiting list. The school may well give priority to siblings, so having elder sibling in the school will be a bonus and may mean you are near the top of the waiting list.
I think you do need to be thinking in terms of younger sibling having to go to another school for what might be a long period of time if it is a school when few pupils leave. The other alternative is to ask the LA where you are going to live which primary school currently has places for the younger child (as an appeal for year 5 should be easier) and also places for both.
I am based in the north west so if you want any more specific information please PM me.

Thanks so much - you have helped me clarify what I thought was correct! It's a school where there is often movement, especially in R and Year 1 & 2 - big city, relatively transient population etc