New Allotment and adding topsoil

Hi Everyone
Im new here so hello to everyone, am looking forward to being an active member here...although I suspect I may just end up asking a lot of silly newbie questions to start with, and to prove a point here the first of what Im sure will be many

I am just about to take on an allotment, this is to be a new site (used as an allotment site 80yrs ago but grass field since), when we take it on it will just be marked out and grassed. We hope to be on the plot early april. My plan was to build lots of raised beds and fill with topsoil to get a quick start on the plot. I have sourced some topsoil from a skip company- £70 for 3tonnes. Has anyone any experience of using this type of screened topsoil and would you reccomend it?
About the beds, I was planning on building them with old wood/new wood from wood yard if I cant get any old and covering with some kind of preservative, any tips on which preservative is ok to be in contact with fruit/veg? and how high would you make the beds?
sorry for all the questions
thanks
Jim

The ground is supposed to be quite heavy clay, I thought that this might be a way to make a quick start as wont be able to do anything at all until april and would like to get some growing done this year

Good evening Jim and welcome to the site. You don`t get out of digging that easy. Even if you buy soil in, you will still need to dig over the soil in the bottom of the beds.

I would say about scaffolding board height - 9"-1ft possibly. I have heavy silt and it is the best option to have raised beds. I still double-dug the ground after skimming the grass off to help with drainage but I don't walk on the beds at all. Don't bring any sub-soil up when digging and get as much compost, manure and grit in as you can.