This is not an Avios deal, but we are also covering good UK deals from all sources on Head for Points.
Lufthansa is giving out evouchers for £20 off your next flight from London, Aberdeen, Manchester or Birmingham. Book by 3rd June for travel up to 30th June. This is notionally a Jubilee promotion, but they do this on a regular basis. Usage of multiple email addresses results in the receipt of multiple vouchers!
You can book via the standard Lufthansa booking page here.