V-Spec,.......... bring warm weather gear, my clothing I've been wearing in the Winter is bottom half, Thermals, Winter lined trousers, waterproofs. top half Thermals, very very thick wool shirt, body warmer, very thick fleece, and a breathable waterproof coat, rest is thermal hat and gloves, and a snood or scarf for your neck.
Last Friday I had that lot on, on what was supposedly the warmest day of the Year!!!!!
I was freezing all day, it is always windy up there.
Then food and a flask of hot liquid, and your set for the Day,
You need to be up on the hill in position by 9.00 AM, its a 30 to 45 min climb from the car park to the position on the hill, allow 45 min if you've not been there, before.
Don't let all that put you off, you'll have a great time, if Possible come for more than one day,
300mm is more than plenty for CadWest, for your first trip, keep your Camera bag light as possible, as it is a steep climb.
Martin
Edit for 600mm info
Worth bringing if you are planing doing wildlife shooting on another Day, its to long and heavy for CadWest.
There is a place Called Nant-yr-Arian 30 miles away where they feed 200+ Red Kites @ 2pm every day (3pm Summer time)
well worth a visit with a long lens.