Depending on time of travel from Gatwick there are trains to Watford
where you can change into a train direct to Liverpool which avoids the
underground.

Sorry, misread that, change again at Crewe.

Time of travel doesn't matter too much, the service to Watford
Junction runs hourly all day, every day. It's only at night that it
doesn't run.


http://www.nationalrail.co.uk/ may help some more. Re tickets, check
out the "Britpass" which has to be purchased before arrival in the
UK. I don't know the options on it or if it will be cost effective.

http://www.raileurope.com/us/rail/pa...ecutive_pass.h
tm