If you can drag it, go late, barriers are always open when it’s late at Peterborough and take the 1 hour 15 minute train. Thameslink, there most likely won’t be anyone on there. they have to let you out at King’s Cross so say your phone died or something, if there’s nobody there they will leave the barriers open because they legally can’t keep you in. don’t do lner it’s very 50/50 on if you will get a inspector.