Upgrades to a Genesis Croix de Fer

Hi all, I’m looking for some advice. I’m pretty new to cycling and have been riding for around a year, clocking up 4,500km since January. I have a Genesis Croix de Fer 20 2015 model which is my do everything bike from club runs to sportives to riding through the woods. I’m planning to do some longer rides this year (including the Tour of Flanders sportive that I’ve signed up to) and while I’d ideally like a new lighter bike for summer road riding and use the CDF for winter / mixed terrain, space and my wife’s patience will not accommodate a new bike at present, so I’m looking at upgrading the Croix de Fer.

From reading around, wheels seem a good starting point (although other suggestions are welcome!) I tend to use the 35mm Continental cyclocross speed tyres that it came with for winter / woods and put 28mm Schwalbe Durano tyres on it for road riding, so another attraction of a second wheel set is leaving one shod with knobblies and one with slicks for quick changeovers as conditions / mood change. 

The stock wheels are based on Alex Rims XD-Elite rims. I can’t find very much about them online. 

So far I think I’m sold on the Hunt 4 Seasons (although I can’t make my mind up between the road and gravel variants) but thought I’d see whether anyone had any better ideas. I also looked at the Wiggle Cosine discs but discounted them as I like the idea of supporting a British manufacturer (part of the reason I bought a Genesis in the first place) and the reviews of the Hunt wheels are so good. 

Is there a more worthwhile upgrade? Or will new wheels not make that much difference, so I should put the GAS (gear acquisition syndrome) on hold, and enjoy what I’ve got?