m.s,
As the others have mentioned, the chargers for your iPhone and iPad will be designed for multi-voltage operation, so all you'll need is a simple U.K. Plug Adapter to connect those to the outlet. I'd suggest packing at least one (or two) along on the trip, as not all hotels may be able to provide them. They're cheap and light, so not a problem to pack them along. On a trip costing $5K or more, $10 for a couple of Plug Adapters is not going to break the bank. The model shown in the link from harley would be a good choice.
The digital camera charger is probably also designed for multi-voltage operation, but it would be a good idea to verify that by having a look at the Input Voltage specifications on the charger. Some older cameras were designed only for operation on 115 VAC.
If you're only travelling in England, you'll only need one type of Plug Adapter. However, if you'll also be travelling on the continent another type will be needed.