I wondered who had bought it. Did the seller give you the following information? 350309 was delivered on 5-3-1957 to J L Blakemore, Plascyni, Berriew. Let me know if you need anything like owners manual, parts book etc. I will see if I have any side panels in my spares pile.
Before starting ensure machine is in neutral and tines are disengaged to avoid any accidents. Turn fuel on, tickle carb, open throttle a bit then wind starting handle. If engine has not run for some time it might be a good idea to check for a spark at plug before starting. Once engine is running check for oil flow as said by hortiman.
Not sure if a workshop manual was produced. The owners handbook includes a parts list for the machine. There is a separate manual for the Villiers engine.
If it has the original JAP engine then it should be possible to get the year from the engine number. JAP used a letter to indicate year. See JAP engine numbering