I went local authority in a roundabout way for both (separately and ten years apart). Slightly different in that I had known of eldest son through work (Portage Worker) and had him on respite care beforehand. Youngest (stranger adoption through LA) I have heard that proper agencies give much more after adoption support and that is what you will need. Also getting everything signed and agreed before going ahead with actual adoption at court. I waited two years with eldest until adoption allowance, hoists and lift were all in place. Good luck on your journey. It is very hard work and not for the faint hearted. Join therapeutic parents on facebook and get a head start.
Mum to AS Big Fish (19, 16 years at home) and AS Little Minnow (13, almost 6 years at home), came separately, and now a wonderful, feisty horse who lets me escape from kids with attitude and the drudgery of disability services and a top of the range adapted van provided by the council fulfilling their legal requirements!