Get him to see a GP that is the inital step, the will then be given an abortive medication which might be all he needs however if he has frequent migraines the GP can prescribe preventative medication. If these options don't help then he can be referred to a Neurologist, preferably one specialising in primary headache and migraine. The hospitals have a range of treatment options not available to GP's to try.
Thing that I find useful for my chronic migraines are ice packs or hot water bottles (careful not to freeze or scald yourself), standing in a hot shower, tiger balm, a dark room, sleep, sun glasses and at times a can of full sugar cola and a packet of salty crisps, taking medication with cola and crisps seems to make it work faster. A tip my neurologist gave me was 3 Aspirin and a can of full sugar cola can abort a migraine in a pinch. This works best if you typically avoid caffeine most of the time as caffeine is a vasoconstrictor, and this property helps relieve the pain and you are more sensitive to these effects if you don't consume caffeine daily.
Avoid pain killers with codine, they can help once in a while but any regular use can result in more frequent headaches.
Lifestyle is also critical so keeping regular sleep and meal times, staying hydrated, avoiding alcohol, too much stress, getting regular low impact exercise. Some people find cutting out certain foods helped but to be honest as a chronic sufferer who has tried various elimination diets I have never found any foods which trigger my migraines and my neurologist (a migraine specialist) agrees that food sensitivities that cause migraine constantly are not something he finds in his clinic. Skipping meals or caffeine seems to be more critical. He could try keeping a food diary to see if he can find a trigger but even better would be to keep a diary of all potential triggers and attacks while he waits to see a doctor. However while a period of diary keeping can be useful too much obsessing over triggers and migraines can be counterproductive.
Generally migraines happen when a range of triggers occur so if he is stressed, has skipped a meal and then not slept well a migraine is more likely to happen. He needs to try a limit triggers to avoid triggering attacks as migraine is degenerative i.e. the more migraine attacks you have the more likely you are to have more migraines, effectively your brain wires in the migraine response to stressors. This can of course be reversed by medication and lifestyle changes and migraine is rarely seriously harmful but if he can avoid becoming chronic he should do that so he needs to do the lifestyle stuff as well as medication, years of just using medication and not changing my lifestyle left me disabled with migraines for many years.