Thanks very much for all the help one last question my cooker wire which is on a separate fuse box is a switch ( for cooker ) with a plug I want to change it for just a switch which would be hiden in a cupboard and then a wire up from the switch to two single sockets is that possible ?.
It's possible but there a provisions.
Normally cooker circuits are configured using the radial type circuit, which lends it's self a little more accommodating to the extension of and additions of spurs.
You must not make the isolator inaccessible, but providing the demand of the cooker is as you have stated via a 13A socket out and the rating of protective device allows the extra demand of the additional socket, the circuit could be extend, through the supply side of the isolator, thus the only socket isolated by this is the cooker socket. I am personally a fan of keeping the cooking appliances on an independent circuit. But that is me!
Please note that any additional sockets should have 30ma RCD protection as should in most cases any buried cable, if your existing Consumer unit already protects the circuits with 30ma RCD, that you are adding sockets to, then no additional RCD protection is not required, but any newly installed sockets and cable buried less than 50mm within walls, unless mechanically protected will require this.