My takeaway from this is the whole English Vs British thing is absolutely nothing to do with your racial background and is entirely caught up in a classic British / English / UKish fudge! Most brits don't know what the different terms mean anyway, unless there are local separatist tensions, so perhaps you and your husband can go easy on each other.
FWIW I always think of a hierarchy:
England, Wales Scotland and NI are countries inside the conglomerate country called the United Kingdom of Great Britain and Northern Ireland.
The UK is often shortened to Britain. We used to have GB stuck on our cars to drive abroad, but that got corrected to UK a few years back. Our ISO code is still GB though....
The United Kingdom of Great Britain and Northern Ireland. title seems to exclude a bunch of islands that are in the UK sovereign country.
The British Isles includes bits that are not part of the UK (Isle of Man, arguably the channel isles, certainly Ireland).
The UK has various associated territories like Gibralter, and Falklands. I can't remember if they count as being UK citizens, but are termed British Overseas territories.
Isle of Man and Channel islands can be called part of the British Isles, but are not part of the UK, but are known as British Crown dependencies.
I think Great Britain is a geographical term than refers to the land mass of England, Scotland and Wales but excludes any islands (e.g. the Isle of White). So take those GB stickers off your (old) cars!
Looking for our country in a website list is like going fishing. What letter is it under: U? G? B? E? (I've never found a list with the preceding "The" but there must be one out there somewhere to confuse things)
Wikipedia has pages devoted to this stuff.
I both love and hate the confusing terms!