if it is PF - there are other conditions that can cause similar discomfort so you really need a professional assessment to tell - then it can take some time to resolve. I guess the internet has told you that already. some people recover from PF quickly, others can take ages - I've been suffering with it since January as an example.
rest is the obvious first choice with foot massage and stretching the plantar (loads of advice in t'internet). once it feels OK again, then try a gentle run and if pain returns, the stop and rest again. it might be useful if after a period of this and it's not improving, then getting some professional advice. they may suggest solutions such as orthotics, night splints (keeps the plantar stretched in bed) or even cortisone.
you can still keep fit by by cycling or rowing machine but thet doesn't help for full marathon training as they aren't impact sports like running.
for me, rest, stretching, night splints and a change of running shoe has helped and I'm getting back to sopme decent miles but I know I still have a way to go.
and you don't have to pull out of VLM yet - you have 6 months to get ready. give it till the New Year.