As per information given by ranasherdil Bhai.
Your minimum budget should be around, if you will be 8 memebers
Travelling : Rs. 3000/head Lhr-RWP-MZD-KERAN-SHARDA-KEL and back to LAhore= 3000 X 8 = Rs. 24000
Hotels : Rs. 1000 X 6 = Rs. 6000 (Cheapest possible)
Meals : Rs. 2000 daily X 7 days = Rs. 14000
Other Exp. = Rs. 3-4000
Total For 8 Persons 7 days(6 Nights) = Rs. 48000
Above is minimum amount required with staying in cheap hotels, travel by bus, no jeep travelling,
If you will be 8 members then you can manage your tour of Neelam valley with Rs.6000 X 8 for 6-7 days.
And if you will feel that your are going to face shortage of funds then you can start return Journey.