Can i do a psychology degree with these a-levels?

i was gonna opt for a psychology a-level along with biology and english but the school im at no longer has psychology a-level seats available so i have to take economics instead. however i do find economics quite hard?

No universities requires you to have studied Psychology at A level in order to join their Psychology degree - simply because not all schools offer it, so to make it a requirement would be unfair.

Some state a requirement for maths or a science (which would be fine, given your Biology). Occasionally you'll see a requirement (or preference) for two science / maths subjects - but there aren't many of those. In the majority of cases, there are no specific subject requirements.

So the subjects you'll be doing won't be an issue from that perspective. More of an issue is your "however i do find economics quite hard" comment. Universities will want to see decent grades in whatever subjects you take. You say "i have to take economics instead". Is that literally the only subject with available space?