Streaming sites for what... tv, music? It is possible to tether from your iPhone but there are some things you should know. You need to check with your cell phone provider to see what their terms of service agreement are. I noticed you’re in the UK so it may be different there. For example, here in the U.S. AT&T offers a tethering plan so to find a way to tether without paying for their tethering plan is against their terms of service. If they catch you they will warn you to knock it off or enroll you in a tethering plan and if you still happen to be grandfathered with the unlimited data you will lose it. If your iphone is jailbroken there is pdanet and mywi (probably a few others) that will allow you to tether. Some will argue that if you rarely use it you won’t raise any flags with the cell phone provider but that is a risk you take.