Double barrel surname- only using one

[Ellllx]

I’m currently 25 weeks pregnant with my little girl and started thinking about names. I’ve got two choices for first, 100% for middle but really struggling with her surname!!
So she was having her dads surname as we were together and getting married, until he’s cheated on me throughout pregnancy and we’ve split and I don’t think he’ll bother with her.
I have a double barrel surname - my mum and dads surnames, and have always hated how long my name is and I just don’t like my mums surname, people always get it wrong.
My dilemma is, can I just give her one name from the double barrel? Only one sounds nice with chosen names too!
I’m completely clueless, someone please help. If you’ve done this, know someone or can let me know who to speak to officially!!

Yes you can give her any surname you wish. Doesn't even have to be one of yours.

Forgot to say
All you do is go to register her as normal and then tell them her name no need to "prove' any entitlement to surname

Okay that’s great thanks!! I just had no idea and everyone I asked didn’t know either, wasn’t sure if I had to like prove my last name or something. Thank you!

It is better if the child has the same name as the mother. Why not change yours to match the child's.

Ive already got my passport and house and everything in my name though so then I’d have to pay to change it all, whereas If I only use one of my names we still share that

Sounds great!

My mum has a double barrelled surname of hers and my dads surnames but I just had my dads surname. I do have my mums surname as a middle name which causes all sorts of headaches and now that I am married, I am know by 3 different names. Slowly getting round to changing everything to match up.
Coincidently I also have a double barrelled surname of my dads and my husbands surnames but our baby will just have my husbands surname to save any confusion.