Our central heating is broken and so we're currently using our
woodburning stove.

I'd like it going when we get home, but don't want to run it all day.
Ideally, I want it to light a couple of hours before we get back in the
evening.

I can't find any gadgets to do it, and can't think how they'd work
anyway. My only idea so far is a long candle, lit in the morning, that
some hours later burns down enough to light the kindling.

Any better ideas welcomed!