You're in the right ballpark, now it's more a question of personal taste as "strong bitter" covers such a range of beers, it's more a dumping ground than a coherent "style". Personally I'd
either up the bitterness a little from BU:GU 0.65
or play around a bit more with the grist. Nothing crazy, just a little brown or amber or something. And either way, a smidge of chocolate is nice, but only a tiny amount, like 0.8% or something.
And personally I would reduce the ABV a bit, but that's just because I tend to only drink British styles from cask, which generally means nothing more than 4.5%. But that's just what I'm used to.
And as always with British beer, don't overdo the carbonation.
As for hops: Never used Goldings Cobb.
Cobb is just one of the "official" Goldings clones, so you have probably bought some under the Goldings label in the past - it's one of the better yielding clones. Are those the
Brook House ones that Malt Miller are selling? I've heard good things about them, but at the end of the day they are just Goldings. (nothing wrong with that, Goldings are great even outside Kent, just trying to set expectations)
The heatwave means that in general 2018 British hops have quite a "hard" bitterness, unfortunately the weather broke before the aromas could really develop. The 2018 Bramling Cross seem to have been particularly affected, the ones I've had don't have much of the typical blackcurrant fruitiness, they're much more like their Bramling mother (another of the Golding clones) - if you want blackcurrant then you're better off whirlpooling some 2017 Bullion.
