AN UPDATE!
I'm not in Seville yet, that's tomorrow hopefully.
I got an email yesterday to check in online which I've just done.
The online process checked me into BOTH flights. For the LBA-AMS leg I could choose our seats. No choice of seats for AMS-SVQ but that's fine.
On the boarding passes it says in Amsterdam it's 'Zone 3'. For the LBA pass it says 'Zone 5'. No idea what these refer to.
Now I've just my fingers crossed for no delay in Leeds as it still feels fairly tight to me.
Many thanks for your input everyone. After the shoddy information I received from both airlines you lot talked me down from rebooking.