You're having a problem with the scope of the $Ip variable.
You increment the number ($Ip) inside the function, that change will be gone when you exit the function.
One solution is to make that a global variable ($global:Ip),
or change the script like this
param($Count,$Name,$Type,$Ip)Connect-VIServer-Server10..*.*.*-Protocolhttps-Useradmin-Passwordadmin2..$Count|Foreach { New-vm-vmhost007.london.england.eu-Name"$Name$_"-Template$Type-DatastoreData_base007
}read-host"Press Enter"2..$Count|Foreach { Start-VM-VM"$Name$_"
}read-host"Press Enter"2..$Count|Foreach { $VM=Get-VM"$Name$_" write-host"$Name$_"
$ESXHost=$VM|Get-VMHost
$secpasswd=ConvertTo-SecureString"formation"-AsPlainText-Force
$GuestCred=New-ObjectSystem.Management.Automation.PSCredential ("formation",$secpasswd) FunctionSet-WinVMIP ($VM,$HC,$GC,$IP){ $ps1="c:\ip.bat $IP $VM"
Invoke-VMScript-VM$VM-HostCredential$HC-GuestCredential$GC-ScriptTypebat-ScriptText$ps1 } Set-WinVMIP$VM$HostCred$GuestCred,$Ip
$Ip++
}