YES!
You can do LASER to correct your eyes, then go to USA to get 1 class (you can also don't tell it to them, no metter for they) and get CPL; then come back to Gatwick for your visit.
It's not a Gatwick roule to apply renewal limits for an initial visit, and it is not written anywhere, but as you hold FAA CPL, they will be free to apply renewal limits at their own discrection and they are really helpfull with pilot
After UK 1 class you can do training where you want where is mutually recognized UK.
For example with 1 class JAA got in UK it's not possible come in Italy cause it is not good here: you need to do again medical here in Italy and you will not pass because in Italy laser surgery is prohibited!