Clothing/Shoes/Weather Gear: If you want to go anywhere near the lake, take some shoes that you can wear in the water to avoid treading on all the stones!
Toiletries and Medical Supplies: Be wary of your dog's paws too and consider taking something to help a hurt paw (Barney cut his paw in the water)
Lake district means walking(if you have any sense)
Luggage and bags: holdall will do, A rucksack is essential for carrying your daily supplies whilst out and about
Clothing/Shoes/Weather Gear: casual clothes,fleeces t-shirts etc, walking boots and good waterproofes, hat and gloves if you intend tackling any of the higher peaks
Toiletries and Medical Supplies: Insect repellant, blister treatment , basic first aid kit to care for scratches , grazes etc.In the summer dont forget suncream.
Photo Equipment: As many spare rolls of film/memory cards as you can lay your hands on-you will be taking photos constantly!
Miscellaneous: If you are self catering take a basic "storecupboard" selection with you as there are no supermarkets in the ullswater area and the local shop has a pretty poor selection, so tea bags,pasta and sauces,dried milk etc will be handy