Aer Lingus normally departs at one of the nearest sets gates to T2 Flight Connections. If it's Dublin, it's usually A21 at the moment, which is 5 - 10 minutes after security. You have to go through the UK+Ireland border in T2 even if your T5 flight was domestic. You have enough time, you would make the EI flight so long as you had about 60 minutes when disembarking at T5.