You've got the VHF, as long as you only use it in extremis then I wouldn't worry about a certificate, limit your calls to genuine Pan-pans or maydays and I can't imagine anyone having a problem.(and if you get fined after the rescue would you care?)
As to the twats who say that safety has no price, bollocks, if I'd waited until I had the money to equip a boat to moderate safety standards I would have missed out on many years of sailing.
The instruction book of most VHFs gives you more than enough information to stop making a prat of your self.
-------------------- "English life at home is complementary to life at sea: security and monotony are its essential characteristics."............Elias Canetti.