I am using CURL to check for the existence of a URL (HEAD request) but when I test it with www.google.com, it redirects me to www.google.co.uk - probab
You could use www.google.co.uk directly, no difference there. google.com/.net always redirect to your location but if you use a country TLD like .co.uk it will not redirect.
There is no way (known to me) to prevent the redirect when using .com or .net.