I tried Tin Plating solutions available from Farnell(V nasty chemicals though)..
Turned out good boards,but if you left them open to the air for a few days they became impossible to solder to..

So I made a solder wave plating box (10w x 2d x 1.5h inch solder bath with a kettle element underneath to melt the solder) and a rotating brass rod (1ins Dia) in the middle.Once the solder has melted I turn on the motor to spin the brass rod creating a solder wave on the roller..then coat the boards in plumbers flux,and run them across the roller.
It produces excellent plating,and board's that are a joy to solder to.Okay with FR2 and FR4
Its very similar to sm wave soldering machines,in a homemade way.