oh hilda i loved dd2's walker. she started off with a kaye, and had it for a few years (we had to do the to/ from nursery bit, although they funded a standing frame for nursery). then they decided she should try without it to see if it would encourage her to walk independently.
the year we didn't have one (just before school) was awful - it was heartbreaking to see her much less able because they had taken away her walker, and she really wasn't ready to walk - she could fling herself across a room (think just early toddling when they can't stop) and then have to grab at someone/ something to stay upright.
so after a year we went back to a walker (she had an r82 croc for school - it was awesome, much better than a kaye) and that gave her the transition she needed. just another year and she was fine. she's been happily independent since.
i loved the independence she had with a walker. and so did she. i remember her being soooo excited to walk the full length of the promenade when we went on holiday to the isle of wight. she literally grinned from ear to ear the whole way, with all of the other holiday makers grinning and waving back because they could see she was just having the time of her life.
i should warn you that a walker is every nursery child's favourite toy though, so there will be queue of kids wanting a go...
when she got competent, she would speed up and then lift herself up on her arms and sit on the back of it, to whizz along with no legs
. and the reason we had to get the croc because she wanted to reverse and turn on a sixpence, and the kaye really wasn't up to the job.
dd2 'just' has physical difficulties. 
ot was good for dd2 (still is). she does have fine motor difficulties and is mostly using a net book now, but they were great for sorting out adaptations. she needed a bar around the toilets so that she could balance etc. and they assessed the school for yr r and made sure there were dd2 height handrails on all the stairs. (she had 1-1 and the policy was that she would use any stairs last so that she didn't get bumped and jostled. this policy didn't extend to her new school in yr 1, despite me telling them, and she went over backwards on the stairs and took out the TA as well....) they were great at getting loads of different cutlery together etc and seeing which ones she was most able to get a grip of.
have you got a bike trailer? the kaye's do fold, so it would probably be fine in there (i think i used two webbing straps and fastened the back to the horizontal bit of the trailer?)