At LHR:
Wake vortex on departure only applies in the following cases:
Leader Follower
J (A380) H/M/S/L
H M/S/L
M/S L
From the same take off point, it's 2 minutes (apart from J followed by M/S/L when it's 3 minutes), add a minute if the follower departs from an intersection further down the runway.
As Talkdowman says, WTS is one part of the departure separation game.
Assuming WTS does not apply, various other separations may apply:
IFR separations (can be applied without radar, determined by SID route and speed group):
- 1 minute when routes diverge by 45 degrees(ish)
- 2 minutes when they don't.
Reduction in IFR separations:
- By using radar, we can reduce the separation between any diverging aircraft (i.e. this cannot apply when successive aircraft follow the same SID) to 3nm when the following a/c paints on the radar following departure (we tend to use this on pairs of a/c that diverge less than 45 degrees).
- By using visual separation, we can reduce the separation between departing aircraft, providing we transfer the aircraft to the departure sector when they are 3nm apart and increasing (we tend to use this on all diverging a/c if the weather is good enough, especially on those 1 minute IFR separation pairs that, if Mediums, we can get down to 45 seconds).