Took a little bit of time but I have gotten Brands Hatch from F1 2013 working in F1 2014. Fully tested in time trial and over a long race weekend with full qualifying and 100% race distance and have found no problems.
Simply unrar the included files into your F1 2014 directory and you are good to go.
Includes: Brands Hatch track files, updated database to enable Brands Hatch and an updated language file to include Brands Hatch.
F1 2014 Brands Hatch 2.0
Brands Hatch fully playable for F1 2014