I'd take his name cos mine is 4 syllables long so double barreled is totally impractical, and I want us all to have the same surname! I KNOW that it's not feminist but I'll keep my feminism to the important practical stuff like both having career opportunities and sharing housework! Yes, we've talked about getting married, he's looked up the financial benefits, I just think he's a bit hesitant ATM because we have other things to think about!
Deciding on your our name, and your child's name is an important feminist principle. Our son has both our surnames, totalling six syllables and both names are foreign it's never been an issue. I notice quite a few children in his class also have both parents' surnames.
Forgive me for thinking this and the fact that you seem to think he would be doing you a favour by marrying you still sounds as if you feel apologetic about the pregnancy, and are trying to appease him.
Who is going to look after this baby once it arrives? You say he's taken a UK job which will involve him being away a lot, so I assume you are thinking you will be the primary carer, at first. But as you're moving back to the UK from a job abroad, you won't have a maternity leave/pay package, so you are already financially disadvantaged. Hell would freeze over before I would become an unmarried SAHM.
You seem to be thinking that 'rushing to get married' is some kind of frivolous girlish dream of bridesmaids and wedding favours -- it's the most straightforward and easily-achieved form of economic protection for you, and if you were already committed to a life and children together, slightly down the line, you should do it now, quickly and cheaply, and have an expensive celebration later, if you want.