Thanks to all for lots of helpful advice. As a novice/ignoramus on these matters, it's also interesting to me there are such a wide range of views...
The main things I'd take from what people have said are:
1. No one knows what's going to happen, so diversification is the name of the game.
2. The big risk (in my circumstances) is inflation.
There are a few things I'd like to ask on the back of that though:
CURRENCY RISK Seems to me (as some posters have argued) that, since I eventually want to buy an asset in sterling - a house in England - messing about with other currencies is too risky. It might make me some money, but it might lose me some too. If I was an investor/speculator that might be fine. But all I really want to do is hold onto what I've got with an eye on an eventual house purchase. I can see there might be an opportunity cost. But why would I take the risk? Am I missing something?
BONDS A couple of people recommended corporate bonds as a good investment. But doesn't their value fall if interest rates rise (which seems very likely at some point)? I know the yield rises at the same time, but I am only expecting to be in this for a year or two...
INFLATION AND INTEREST RATES As far as I can tell the real risk for me is less high inflation per se than negative real interest rates, i.e. that inflation is higher than the interest I'd get on any savings. I think this risk arises whether the nominal rate of inflation is high or low. And you could argue that's where we are now, with CPI above base rate, couldn't you? Sorry if this is a dumb question, but how do you hedge against negative real interest rates?