Invest in property to let, here or elsewhere in the world. Buy some gold. Invest in nuclear and recycling companies.
....Or make sure you choose a pension fund which invests in these things. You have to be active. You can't just bung pension money at an insurance company and leave them to it. You have to learn about pensions and get involved. You have to choose the funds for investment carefully and keep reviewing and switching your funds. If the pension company doesn't allow it, move elsewhere.
I'm not going to post the actual sums but I'm very happy with my funds performance. It is growing at over 12% per annum.
Don't forget the tax relief on contributions is worth 41% - although the government can of course change this. It'll be a different ball game if that happens.