Instead of a turkey, could a chicken be brined? It will only be my brother and I for Christmas dinner and a turkey is really too large.
It is possible to brine a chicken, though some people will suggest it is not strictly necessary as the cooking time for a chicken is fairly short, compared with a turkey, and the risk of the chicken drying out during cooking is very much reduced. However brining does help to flavour and season the chicken, as well as adding moisture, so if you would like to brine the chicken it should be fine.
You will need to make a smaller quantity of brine (roughly half of the quantity in Nigella's turkey recipe) and as a chicken is smaller than a turkey the brining time will be much shorter. We would suggest brining a 1.8-2kg (roughly 4 pounds) chicken for 3 to 4 hours only. If it is in the brine for too long then it could become too salty. And remember that you won't need to season the chicken with salt before roasting. If you prefer to brine a turkey breast (on the bone) then allow 2 to 3 hours in the brine.