I haven't had a T5 connection but I'm guessing she'd have to do immigration in LON? Which definitely wouldn't be enough with just 60 minutes and a language barrier would add stress and complications. I have some friends who have non english speaking family and what they do is write out specific phrases that she'd need to relay to others in both languages. Put them on Flashcards and she can hand then to whomever she encounters for hopeful assistance. Guessing she speaks Hindi but that's just a guess.
IE.
Hindi- मैं 20 गेट के लिए देख रहा हूँ तुम जिस तरह से बात कर सकते हैं
English-I am looking for gate 20 can you point the way?