Here is the chart for ILS 09L at Heathrow.
Inbound track (heading) 091 and you need to be at 2500 ft about 8 miles out to intercept the ILS.
So you generally maneuver the aircraft into a 20-30-40 degree (what ever works) intercept on the localizer 10 miles out (or longer, if you want that), and then follow the glide after you have established on the LOC.
http://www.ead.eurocontrol.int/eadbasic/pamslight-D72D15FFA392BBF39FD7F69F210EC9BC/7FE5QZZF3FXUS/EN/Charts/AD/AIRAC/EG_AD_2_EGLL_8-1_en_2011-03-10.pdf
I highly recommend using the charts. Real pilots use them for a good reason.