My First Allotment is All Grass ... What advice can you give to get me started?

You will get wireworm and cut worm in your first year.  We had a similar situation when we took on ours.  It had been a pasture and the allotment areas had been turned over by a plough, turning all the grass and weeds in.  Fun.  So take it slow and use your first year as a clearance year - of weeds and pests. Crops are a bonus. Love the robins who do a good job on the worms, clear the perennial weeds by hand if you can (defo don't spray if there are flowers.  You will kill bees as well as chickweed, dandelions, speedwell, whatever) and hoe off the annuals as they germinate.  Raise your plants at home and plant out when sturdy little things so they don't just get eaten at soil level.  Squashes, courgettes etc are great ground cover and robust by the time they are ready to go out.  Carrots and parsnip are hopeless in your first year.