If your iPhone is displaying a message saying "SIM Not Valid", this means that your iPhone is still locked to your home network, and the UK Sim Card will not work.
We already told you on many occasions that you need to unlock your iPhone.
Sorry but we can't help you unlock your iPhone. You'll need to contact your telco provider to request an unlock of your iPhone.
To unlock an iPhone requires you to have connected your iPhone to iTunes and perform a full back up and restore of your iPhone. If you merely requested your iPhone be unlocked, but did not perform the full back up and restore in iTunes, then your iPhone remains network locked.