Thanks House. I found this out after calling the Sen line
The agent said i could use the 2 EVouchers outbound and use miles inbound but not really an option as i only got the EVouchers through UK Comp and i am sitting at a lowly 0 miles but i do have a trip on UA to SEA in Sept.
I could use the UK promo vouchers on the rtn from DXB if available seats and it is an H Fare.
Thanks
Alan