Thanks Phil Strangely enough, I did realise both can be used in English... it was more a question of usage.
I was thinking the one form wasn't used much because I compared Google results for "wedi mwynhau" with "nes i mwynhau" - now I realise it was my bad grammar/spelling that was the issue! "Wnes I fwynhau" comes out with a lot more results!
Still feels like there's some difference to Englisg in usage of the perfect when it comes to things that happened that same day... E.g. I wouldn't say "I have enjoyed meeting you today" if sending the person a follow up email several hours later, but it seems in Welsh the perfect is ok in that scenario, am i right?