What happens in the second wave with tamiflu?

Forgive me if this has already been answered. This is the first thread I've started and i'm really interested in your opinions and ideas.

From what I understand there are stockpiled Tamiflu doses to treat 80% of the UK population. According to official figures there are 100,000 people with swine flu in the UK right now. I am assuming that quite a lot of those people have been given Tamiflu.
Since the numbers are predicted to increase exponentially before winter we can assume that the amount of people taking Tamiflu will also increase.
According to the NHS direct website Swine flu will mutate in to a more deadly virus in autumn/winter (the dreaded 'second wave'), because the cold is an optimal condition for flu. Because of the mutation the winter Swine flu will be different so it will be quite possible for those who have already had it to catch it again. In effect you will have little or no immunity to the new strain.

So my question is will anyone who has already had Tamiflu be given a second dose if necessary? I was under the impression it was one dose per person and thats it? Surely there wont be enough? Will there even be any left by winter?
I don't like the idea of stockpiling Tamiflu when I don't need it but im starting to wonder if I should store some for my kids??