I've got a 02:10 connection in LHR to a BD flight to EDI. Since EDI is within the UK I shouldn't have to deal with any additional immigration formality so it should just be security. Wondering if I have enough time to use the Arrivals Lounge and still get over to T1?

I know that arrival time can be variable so am curious on others thoughts on the minimum time between arrival and departure to safely use the lounge? Forgive me if this has been discussed before, my search didn't retrieve any useful hits.