Hey!
I went on NCS last year during summer, in the East Midlands area. Depending on where you are in the country would depend on what type of activities you do. Generally the first week is the same across the country, a week at an activity centre (PGL) or camp site. The second week is heavily dependant on the provider but was personally my favourite week. Yours does sound different to mine, you mentioned choosing a a skill for part two, we didn't have that and that's not in my providers agenda for this year either.
For Packing, good luck. I was given a reccomended list but i didn't need most of it, so just take what you want. You should be given t-shirts which are optional for most of the time. You may also then get freebies like water bottles an sun glasses.
Have fun though! It was a great experience for me.
If you have any questions, feel ree to ask as i'm now a Recruitment Ambassador for NCS and have had a hand in organising this years programme for my region.