Here is the info for the Incubus HQ pre-sale for the June 14 show at The Forum in London -
The pre-sale starts Wednesday, June 1 @ 9am and ends Friday June 3 @ 9am - so you will have 2 whole days head-start to try and get tickets.
Pre-Sale Link: http://www.gigsandtours.com/?s=incubus&site=incubus
Pre-Sale Code: kate
There is a 4 ticket limit per purchase, and the number of tickets available for pre-sale are LIMITED, so don't hesitate and keep trying if you don't get through the first time.