peaches and nectarines can be a bit fussy, not liking damp and will need some protection. whereabouts in the country are your folks as this may be a consideration?
I've just noticed the date of your message (even though it's come up on recent threads/ replies...)
If not too late, i really think going to an RHS garden to ask the experts at one of their Grow Your Own or Fruit Festivals is the best place to get advice and buy a good specimen.
If you're not too far from the south, the Brogdale Collection (National Fruit Collection in Kent) might be an option. they have festivals and themed open days for all kinds of fruit, and can offer excellent advice on which variety to choose, positioning and care.
I'm sure the website offers this too if you are further afield, and I'm sure they would be very helpful to email/ phone enquiries.
All the best,