Return tickets cost £22 but if you buy Advance single tickets you can do it for as low as £6.50 each way (per person). I use the
National Rail Enquiries website to check available tickets, but buy them at the station. Cheap tickets sell out so get booking now!
I assume that the trains will be the 'sprinter' type like the ones that run between Hebden Bridge and Leeds. They usually have a bicycle compartment with room for 2 or 3 bikes either hanging from hooks or in slotted stands (look for the bike symbol near the carriage doors). Bikes travel free.
It's pot luck whether you can get your bike in the compartment since you can't book the spaces but it's usually okay. Even if the spaces are taken, you'd probably be able to prop your bikes up somewhere unless the trains were jam-packed. I always carry a couple of bungee cords to help secure my bike.