There are plenty online societies out there all too willing to give you an 'official' handicap which is fine however you should watch as that handicap may not be official enough to get you into some open competitions. Most clubs / competition organisers would look for a CONGU club affiliated approved handicap although I can't recall ever being asked to show a cert or heard of anyone else having to. I guess only if you win will they maybe want to see something.
An official handicap is a selling point for clubs now a days, unfortunately some do still come with the big joining fee attached.
If you are after regular medal play then pick a club to join. If you play regular enough then it will be cost effective in the long term.
-------------------- It's not what's in the bag; it's what's in the head and how you use what's in the bag!