U.K. coach operator National Express will get you from Hastings to York, but will take over nine hours to do so. This compares rather poorly to the five hours the journey would take by car. You can book tickets on the company's website and jump on your coach at Queen's Parade in Hastings or Sedlescombe Road North in the adjoining town of St. Leonards. Your route will typically involve changing coaches in London and Leeds.
Megabus doesn't run coach services from Hastings, but if you can get yourself up to St. Pancras International Train Station in London on the day you want to travel to York, you may be able to bag yourself a bargain with the budget coach operator. As of August 2013, Megabus was selling advance tickets between London and York for the equivalent of just over $12, which compared favorably to the $54 National Express was charging for going the entire distance. National Express was charging $8 to travel between Hastings and London at this time. Combine both firms' knockdown advance rates to make substantial savings. Book early to get the best rates.
Not all National Express and Megabus coaches are fitted with Wi-Fi and electrical sockets, so check with the company you book with if you're concerned about being able to use Internet-connected devices while traveling. Neither firm offers refreshments on their services, but both allow passengers to bring cold food and nonalcoholic beverages. Both companies let you bring hot drinks, as long as they're covered with a lid. You'll be making stops throughout your journey where you'll be able to stretch your legs and buy refreshments, but won't see much more than the interior of coach and service stations during journey breaks. If you're particularly tall, be prepared for some discomfort. National Express and Megabus coaches are not renowned for leg room.
If you want to get up to York quickly, consider an alternative to coach travel. Taking the train will cost a little more, but the journey will take around half the time. The cheapest single adult rail fare from Hastings to York would have set you back around $93 in August 2013, with the journey taking just over four hours. If you want to keep your costs down, try your luck on carpooling sites such as Bla Bla Car, Carpooling.co.uk or Carpool World.