Glad you got on well, guns like yours will certainly be comparatively worse for range & accuracy/spread, but IMO being forced to run in a bit closer rather than cowering behind a tree the second you spot the opp, isn't a bad thing for any newcomer, as being more proactively mobile will allow you to kick ass regardless of what gun you have.
The difference isn't that huge at the end of the day, it's only firing a plastic ball. We all like to think it is necessary to spend 10 times the amount you did (myself included), but it's definitely more of a common standard of luxury rather than a necessary standard to play the game. I kinda think most of the 'that guns not suitable for airsoft' replies to you (and the countless others who pose the question about their 50% orange BB gun) are said because we all want to put off dumb kids who think it's like CoD in person, as they're usually the ones who buy them and they're worst demographic for trying to cheat and other reckless behavior. If they only spent £50 on a gun then it isn't too big a deal for them if they get banned for being a dick head from their local site (probably ruining the day for the rest there in the process), buying a £150+ gun at least means you'll care about whether you can keep using it or not.
Good luck upgrading the AK12, would be trickier than doing so to a 'normal' standard of AEG judging from what mr duck says, which is tricky for any AEG first time and easy to fudge. I personally would get a 'normal' standard of gun like a ICS/G&G and then go back to pimping the AK12 once my familiarity of AEG internals had grown. Would be a shame if you end up having spent £100 on internals for a £30 gun, but can't get it to work properly. It will however be awesome when you have an AK12 with a good standard of internals, it's just a question of whether that time should be now, or later.