Don't worry. Everything is available as soon as you reach Abbottabad.
I did a similar trip for Nathiagali couple of years back. Went from Lahore to Abbotabad from Daewoo express.. As I reached the Daewoo bus stop there, around 3-4 private drivers approached me to ask where I want to go. Told them Nathiagali,and they gave me both options, i.e staying with me during my trip or just drop. Took the option of just dropping there. Negotiated a reasonable price with one (can't really recall the amount but it was v reasonable) and he gave me his visiting card to call him when I would want to return. Didn't need him as I got other options there.