We like to take a block of three weeks or even four for some kind of hiking or running adventure. We have either organized trips ourselves, or used small running companies like trailsrunspain or tracks-and-trails. For example, one holiday was Jura mountains in France running, followed by run the Jurassic coast in UK. Another was Cumbria Way followed by C2C.
Sometimes we use the general-purpose walking baggage companies like Macsadventure. This christmas it's the mountains above Alicante with Mountainwalks. In the summer it was Anglesey and welsh coast path down to Aberystwyth with Contours. These companies will adapt their standard schedules to runners or run/walkers if you ask. It always surprises me how few runners seem to be looking for holidays like this but there are a few around, especially if you take the time to adapt walking holidays.
I don't want to unnecessarily put a damper on things but I would like to suggest you take the word "supplement" literally - you should aim to supplementgood nutrition, not somehow compensate for poor nutrition by taking supplements. The one should be in place before even considering the other.
The only times I might consider adding to good nutrition (apart from chronic dietary deficiencies, like B12 for a vegan) would be cases of extreme load. Possibly in connection with a lot of weightlifting or with heavy running sessions. For example, a protein shake or simply a chocolate milk after a hard session is a good idea.