So uou have … £300 or so?
WHY would you put it into WoW gold? That is seriously a terrible place to put it. Almost anything in the real world would be better.
You hardly need any gold to play WoW. Once you get to 60, you make more than you spend, and you need only a few thousands or tens of thousands at most. (World Top 100 raiders are an exception, but that ain’t you.)
There is nothing like player housing where you can invest in your future status and capability in the game.
When we get past the question of what you need to play the game - repairs, consumables and so on - there are two possible directions to spend more than a few thousand.
Cosmetics.
You can pay crazy prices for really rare cosmetics, especially mounts. But they’re just for show. They don’t run any faster or fly any higher. Most are not particularly attractive - just rare. And when I say expensive, when one of the sought-after ones randomly appears on the Black Market Auction House, it will be sold in minutes for gold cap - 9,999,999 gold.
Yeah, ok, if someone has the gold and wants them, sure, I guess, but a new player should AT LEAST hunt some of your own before you decide to spend £300 on a bunch of pixels whose only value is that it is not common in a game.
There is one mount, maybe two, worth buying: the Grand Expedition Yak for 120K. And/or the Traveler’s Tundra Mammoth for 20K. Both of them come with a mobile vendor on board, which is very handy, and the Yak comes with a Transmogrifier as well.
Those two actually do something for you, unlike all the others.
Some armor appearances can be a bit expensive - there are a few in the tens or hundreds of thousands. But they don’t make you play any better, and you will stop using them when you change your mog.
Boosts.
When you reach 60, you can pay people to boost you through high-level content so that you get very strong gear.
As long as you pay in gold rather than cash, Blizzard will not ban you.
6 million will get you very decent gear (Heroic level + bit of Mythic) very quickly, if you choose your mix of boosts carefully.
And now you will be well geared - not top-tier, but more than you need - with no idea how to play, or where to apply your gear.
And the gear will be out of date when 9.2 comes.
.
Anyway, those are your general choices to splurge 6M. If some part of that interests you, I or anyone else here will be happy to fill in the details and answer any questions about specifics.