Hi I've added a homebrew oath (Oath of the Valkryie) as an option and my Paladin player has taken it. However the spells and actions given to the player aren't in the character sheet. Is there something else I need to do or add to ensure he can see all his abilities on his character sheet?

How did you add the spells & Actions?

Please see the General FAQ #s 6 & 6-B: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).

I didn't, I added it from public homebrew. If you're right I'll have to copy paste it essentially, and add what I need from it

You will need to contact the homebrew’s creator and then swap out your current version for the new one after they republish it. (Either that or recreate it for yourself from scratch as you suggested.