Jackie, I Fostered children for over 8 years, I did contract care a more specialist form of Fostering, I was the first to do it in the area and not sure if it had been done anywhere else in the UK. COntract care was brought into Fostering to provide placements more "difficult" to place young people, I also did main stream Fostering, Emergency Fostering and Boarding out, after 6 years I stopped due to being offered a job abroad, so when my last Foster child returned to their parents, I worked for a Social Work agency and covered shifts in loads of residential units and secure units, then worked in Child Protection so visited families at risk of abuse, so you could say I have a very clear understanding of the needs of a Foster Child. I worked with disabled children also and some were placed for respite in Foster families, there is a great need for good respite for diisabled young people and I saw a lot of sucsessful placements benifitting all concerned.
I enjoyed most of the time I spent fostering and learnt a great deal, the majority were older than 13, I would have loved to have had some younger children or babies, there are different issues with babies by the way, Fostering did have it's drawbacks and personally, I think your age is an asset, I certainly have much more patience than when I was younger. You need a good support network who also understand issues some if not most of the foster children have faced and subsequently the behaviour they display. I am not going to go into details on here and in many way's would do it again, best to meet with some other foster carers for their thoughts and experience. I have met some very naive Foster carers that put their family's and friends at risk.
Now I really must go, although I could say loads on the subject....my advice, HAVE A GO but research first!!