18k avios dependant on availabilty will get you a J-F upgrade. Or 2 EDI-LON RFS tickets. As said it all depends what you want to use them for. There's also the Amex to consider if you can spend 3k in 3 months you will get another 25k+ avios.

Edited to add the Upgrading using avios will work as far as ORD going west not sure about east