Originally Posted by
enviroian
Thanks. I can’t buy cheaper ticket as there is a window of time I’ll get into st pancras coming from lhr. Buying the ticket online I found out is a total waste of time as I need to re-check in with a machine at st pancras so I’ll just use my iPhone at the lhr tube entry and buy a ticket from a ticket office at st pancras.
The benefit of buying online is you could then pick it up at LHR if you have a few mins to spare before the next Tube departs (less of an issue at T2/3, more at T4/5). This would save you having to pick up at STP which could translate into a 30min time saving on a Sunday.
If there's a Tube about to leave, you could still jump on that and pick up at STP.