I was in exactly the same situation 18 months ago. Decided to gradually invest in shares and funds. Wish I'd taken financial advice as I suspect i would be better off. Some funds have done really well (+20%), some have done badly but overall, I'm just about ahead of the game and have a better return than a savings account. The stock market is incredibly volatile though, especially right now, so it's a huge risk.
Classic car values are on the slide too, so I'd be interested, like you, to hear of some better suggestions.
I would start building up your ISA though and take each years full allowance. I assume you have already paid off your mortgage and any other debts?