In reply to MattH:
All-terrain pushchairs - you won't find one that folds up compactly if you really want it to be all-terrain! Mountain Buggy are definitely worth a look, but not cheap. Great for forest tracks/bridleways, but do have their limitations. The big decision is if you go a permanently fixed front wheel (best for true off-road) or one that can swivel (much better for the supermarket) and then lock as required. I'd avoid any highstreet '3-wheelers', as they tend to weigh a tonne! Our little one's been to a few decent summits in his Mountain Buggy 'Urban' - but good local knowledge helps choose suitable peaks. Also great for leaving him with the grandparents for a walk round the lake whilst we head off for a bigger peak - they're not up for carrying him around like we would.
Front baby carriers - we had a Bushbaby one, but I could never get it to be comfortable. IMO, soft slings are the way forward. Take a look at the Little Possums website - I used the Kari-me, and then a ring sling. Suited me much better.
Rucsacs - we got given a second hand Macpac, which is great. Personally, I'd prefer it if the back went a little shorter, but it's a minor whinge. There's some good info on the Needlesports website - as it recommends, walking poles are useful.
Waterproof/fleece suits. Take a look at Togz - best I've found.
Oh, and specialist shops worth a look are Togz 4 Kidz in Keswick, and particularly the Climber's Shop Children's Shop in Ambleside. Both have websites. Staff in the Climber's Shop are really excellent - I'd be tempted to give them a ring with any questions!
Hope that's some help - feel free to email me!