Hi pinkmama, not sure I can be of much use as my dd3 has had a VI since birth and is only 5 so we're not at your stage yet. My dd3 has a genetic syndrome and the support group has been fantastic, I would imagine there would be one for this and would be well worth getting involved with.
There's also your local sensory impairment service that you should get in touch with, they can usually be found on your council website, usually under education, you'll be looking for mention of a QTVI, qualified teacher of the visually impaired as your service may be called something different, they will go into school and offer support there and see what can be put into place. It may be worth making contact with the school senco if you haven't already.
Social services should also offer support as her vision deteriorates and can offer things like mobility training and any technology or gadgets she may need, as well as a card that says she has a vi. The optician at our eye unit does low vision assessments which is worth looking into as well.
There's also a few charities around that you might like to investigate, look, http://www.nbcs.org.uk/ nbcs, victa and of course rnib.
do try not to concentrate on the future, much easier said than done I know! Just concentrate on getting through one day at a time if you can. You often get a very clinical view from doctors about sight loss, they can paint a very bleak picture but there is help and positive support out there.
my dd3 has other sns as well as the vi but you wouldn't say she had a vi if you saw her, she gets on with everything and charges round like any other child I know. There are ways round things and your dd will figure out what suits her best as time goes on.