Broodymamma I think you have had excellent replies. The only thing is I would caution against going to Barnardoes or any other of the voluntary organisations. They will certainly get you on a prep course and approved in no time at all, but they don't have any children of course, so they have to "sell" their approved adoptors to the LA. LAs are so under resourced (and this incidentally is probably the reason your LA is dragging its feet) and now budgets have been slashed by the coalition they are really struggling, with "frozen posts" so they can't advertise vacancies because there isn't the money to pay them. LAs have always placed children for adoption with their own approved adoptors wherever possible because this is the cheapest way. The second cheapest way is an inter-agency placement (some LAs are in a consortium of nearby LAs and they work out a fair inter agency placement fee) the most expensive way is "buying" a family from Barnardoes and other vol orgs.
The vol orgs don't always tell people about this very important factor when recruiting. What age group are you thinking of. The need is usually for older children (middle years age range) sibling groups and children with disabilities, but on the other hand a fair % of children under 5 are placed for adoption. It helps if your offer is for 1 child and 2 if sibs, as children awaiting adoption rarely come without a sib (or many sibs) but of course decisions then have to be made about how to split the children as few people can take on large sib groups and it isn't always good for the children, as they will all have emotional difficulties of one sort or another, given their pre placement experiences.
The most useful thing you can do in my view is to read up on "Attachment theory" because this really is at the root of all children placed for adoption. They will have learned that adults are not to be trusted because of the way in which they were neglected/abused by birth parents. Many adoptors think that love will conquer all and it won't. I suggest you look on the "British Agencies for Fostering & Adoption" (BAAF) and "Adoption UK" and there will be books on the site that you can buy on this important issue. Some LAs will include this in the prep course, but I'm not sure how many do this tbh and it won't be enough for you to really get the hang of it. Not that it's complicated at all.
In essence it means that children who have been abused/neglected in their earliest days, months and years will have grown up insecurely attached to their birth parents or step parents, and this can give rise to all sorts of problems, dependent upon how much they have been affected. Children who are loved and cared for and have had their needs met since birth will have secure attachments to their parents, which will be a protective factor for them through the lifespan. Conversely children who are insecurely atached will have learnt that adults aren't to be trusted, or that sometimes they look after them, and sometimes not, and they become confused and insecure. Adoptors need to understand this and there are specific ways of helping a child to form secure attachments with the adoptors. Mostly there is a big gap between a child's chronological age and emotional age, meaning that a child needs to be able to regress at times, e.g. a 6 year old may be emotionally at a 3 year level and so this needs to be taken into account.
Sorry I didn't mean this post to be so long!