If this is his life-savings, and he's 80 you want to take absolutely no risks with it. In this scenario (unless he has other substantial funds readily available to him) he may need the money at any time and he doesn't have a sufficiently long time-frame to ride out the ups and downs of the property market or the stock market.
Essentially that means a range of high-interest, no-risk cash accounts or possibly savings certificates with no more than a minimal tie-in period (3 months or so). Don't even think about share-based investments or property -- if the investment loses half its value at exactly the time your Dad needs the money then you're in real trouble.
Selecting a range of good cash accounts is not brain surgery if you read the Money section of a few of the weekend broadsheets, the best-buy tables will show you which accounts have the highest interest. Watch out for accounts with high headline rates that drop after 6 months, though some of the papers do tables that show you the most consistent accounts over the past 5 years. Some of the best deals are currently internet-based accounts, but given your father's age you and he need to decide whether he's happy to operate that kind of account himself or whether he's prepared to let you take charge of the investments on his behalf. Alternatively the remaining building societies often have better deals than the high street banks. But you do need to keep an eye out every 6 months or so to check that the interest rate hasn't taken a dive.
If you really feel you need an IFA, go for a fee-based one where you pay a fee for the appointment but the IFA doesn't get any commission. The kind of investments your Dad needs won't generate commission, so the risk with a commission-based adviser is that they either won't take the case on, or they'll steer him towards unsuitable but commission-generating investments.
I've just done a similar thing for my parents, which is why I'm up to speed on it.