We prepared our DS last year by taking him out of school for the week to go on holiday to Spain [terrible mother emoticon]. He had to sit it at a later date.
Seriously though, we had no idea the 'test' even existed. Our week of holiday was authorised by the head and she didnt mention it when authorising our leave. I only realise we'd missed it & it had to be sat later, when the teacher told us at parents eve at end of term.
Don't prepare at all - my son wasnt even that far advanced at reading by the end of year 1 (wierdly shot ahead most of the class early in yr2), and passed it just fine with zero preparation and a week in marbella 