Great Western Coffee Shop

I have a long journey with Crosscountry (BRI to Darlington and Back in one weekend).  I'd rather avoid an AP ticket because the flexibilty might be useful and there is an off peak return for about ^100 which I don't think is too badly priced (and with my last 3 CC journeys I've managed to get a partial refund anyway because of delays).  To make my journey more pleasant can anyone tell me:

1) what the Weekend first upgrade is?  The CC website says "from ^10", but I understand that it could be as much as ^20 depending on the distance travelled).  I assume I can just buy it on the train and don't need to decide before hand.  Am I right in thinking that the upgrade premits a change of train (ie if I change at BNS to another CC train, I will not ned to buy a second upgrade)  What extras will I get?  I assume it is just tea and biscuits sort of thing rather than a meal or any hot food.  IIRC Virgin used to do overpackaged snack boxes.

2) which trains are usually operated by HSTs at the weekends?

Thanks for any input.

Tim

I'm not too sure about pricing, but in terms of the extras you get it's not a lot - tea/coffee/the odd soft drink and biscuits, and that's on the occasions the trolley actually appears.

I've decided to aviod XC all together and travel via London.  Seems quicker, not much more expensive off peak, no Voyagers and I get to try out Grand Central on the way North.