It depends on how much you are prepared to spend on flights and how many Avios you have. I didn't find a 'low cost' option on OW or many other airlines for that matter.

I used Avios at Xmas to go from Leeds to London to Rome - the 1 hour 30 min wait at LHR doesn't bother me at all (Mrs Billy will be happy as larry in the flounge) - as the flights would have set me back over 1500 euro's. Instead it cost me 45k Avios and around 100 euro's in fees.