Hi Nick,
How about a couple of weekends (or just day trips) away?
LON-HEL return on Finnair (via Oslo) is coming out at £490 in CE and will get you 160TP
LON-MAD return on Iberia is coming out at £302 in CE and will get you a further 80TP
I used the ITA Matrix to get those (there's a good guide to the matrix
here), with a routing code of
/ alliance oneworld, both around the end of May / beginning of June.