The message
from Janet Tweedy contains these words:

Where can I get specifically on raised beds for growing vegetables?
There's a couple of things I can't find details on.

Well I've looked at loads of book but even the RHS just doesn't give
enough advice about it all.

There are some very good information services run for wheel-chair and
disabled gardeners, which are sure to cover raised beds. Useful sources,
whether or not you're intending to make them high enough for wheelchair
access.

Janet