Only thing is, if I don't access it for a couple of days lots of stuff
has disappeared, any way of retrieving posts from ,say, the past week?

It is up to the news server you are using to determine how long posts stay
around. My server hold 5 months of uk.d-i-y at present. Others I have used
have only kept a couple of days. If you want to look back further, you need
to find another news server (v. difficult, as you are usually locked into
your ISP's) or use Google groups.

Christian.