On April 18, 2017, we are flying from Salt Lake City, Utah, USA on Delta Airlines flight DL 50 arriving Heathrow Airport at 1:20pm April 19, 2017, on one ticket. Then on a separate ticket, we fly Aer Lingus to Shannon Airport on flight EI 385, departing Heathrow at 2:45PM. Will we have enough time to get through customs, baggage claim and check in for the Ireland flight? How much time will be necessary to make this connection?
You're arriving at Heathrow at 1:20PM and are connecting on a separate ticket to a flight departing at 2:45PM?
Forget it, just forget it, and rebook your connection immediately. There's one at 7:35PM, which you would make. But the 2:45PM one on a separate ticket? You're not nearly getting through immigration, baggage claim, from T3 to T2 and through security in that time, period.