I have recently discovered that our local half marathon (next April) lets you enter as a two person relay... Basically runner 1 does 10k and runner 2 11.2. I don't think an HM is realistic for me by next April, but 10k surely is (I can currently do 7k in an hour.)
The twist in the tail is the race profile. The first leg is flat for the first 5k, then climbs 300m in the 2nd half (long slow slog). The second leg is almost all downhill and takes pretty much all 11k to drop 200m.
It all looks very well organised. Shuttle buses take runner 2 to the handover zone, then collect all the runner 1s and takes them to the finish.
So might need to start practicing running up and down hills. Have some time to decide, but its a thought.
Uploading a pic of the profile for your entertainment !