Your best bet is to use the 8 seater minibus taxis that operate in the Lancaster area. Cost will be about £20 each way, as long as it's before midnight. You could use the bus, but if there are 8 of you travelling, it will be cheaper to use the taxis.
The firm I use are 32090 Taxis. As you can guess there 'phone number is 32090, and if you want to ring them from abroad to check prices, number will be 00 44 1524 32090.
Have a good trip.
ps, if you need any more info, try posting on the Lancaster forum, as more folk will see it.