@Kibosh
OK, I'm in a more or less similar situation as you are. I am Dutch, have a Dutch sim card in my Dutch 920 but live in Portugal. Due to the fact that I bought my first Windows Phone when The Netherlands were not yet on the official list, I have an UK Microsoft account.
Just as a side note; I have my Dutch credit card registered on this UK account and it works flawlessly. Just fill in a valid UK address when you register the card and all is well.
Due to your remarks concerning the WP store I have been playing around a bit with the Location & Language settings of my phone. Eventually I was able to see your reviews! That is, I saw reviews written by ThaKibosh, which I assume is your good self. To make this happen I had to set the Location & Language settings as: Phone Language-Dutch, Country/Region-Belgium, Regional settings-Belgium(Dutch), Browser language-Dutch(Belgium). Obviously this whole list was in Dutch but since this is an English forum I translated it to English. With these settings the Store is also in Dutch. When I leave Country/Region set to UK ('cause I have a UK MS account), the store navigation is also in Dutch but the reviews and Apps are in English.
You also mentioned that Need for Speed installs in French, so I gave that a try as well and downloaded Need for Speed hot Pursuit. The game installs nicely and is all in English.
I would say, give these settings a try. If they don't work as described above you could try to get yourself a UK account, just to see if it works as it does on my phone.