You asked, with regards to tethering, are there ways around this?
And the answer, unsurprisingly, is yes. There are always ways to get around restrictions; to do that which you're told you cannot do; to bypass locks and restrictions etc.,
Howevever, you're also aware, as you have been informed here, and also when you signed your contract, that 'tethering' is prohibited by Virgin. So, even though I know how to bypass the restriction and avoid detection in doing so, I'm not about to post instructions here on how you can do it too. Firstly, this is the wrong place to be asking- on Virgin's own forum, how to get around their no tethering restrictions: that is just rude and disrespectful to Virgin. And secondly, if I was to post instructions, you and everybody else that wants to tether, even though it's not allowed, will do so, and then Virgin have a clear description of how people are avoiding detection and then a target to focus on and the ways to block/detect that methods.