I buy a lot of stuff from Fry's in SOCAL, including my Mac laptop. There are always a load of write-in rebates, sometimes adding up to the price of the kit (minus taxes). The trouble is that I regularly found that up to 60-70% of the rebates never arrived. You can chase them up, but they're run/handled by specialist companies and you get a run around.
To be frank, look at them as a sort of lottery ticket and buy the laptop that's got the best store price.
For a laptop the power supply will be 110-240v 50/60Hz, but it will be a US keyboard. But you soon get used to the @ location. The only hassles are the lack of a £ sign and the small return key.