Posted: 03/07/2014 at 06:56
Ideally you need two ( or three) but if you only have room for one then that's fine. You just need to realise that it may become full so that there may be times when you can't compost your waste, while you are waiting for it to rot down. Being where it gets some sun will help with speed.
Compost bins work quicker the bigger they are but again if you don't mind it being slower a small bin should be fine - you see lots of quite small ones shaped like little bee hives, I know these are expensive but if you have a look it will give you a feel for the size.
Have you tried looking on freecycle, you may get someone offering a compost bin on there.
Some green manures are also pretty flowers such as phacelia. But they are quite space hungry for the goodness they impart so good for beds but not pots. You could let some grow on to get the flowers and dig the rest in when ready to plant you beds.
If growing beans you could dig a deep trench ready and put compost and shredded newspaper in over the winter. You then bury this and plant the beans above. It helps with nutrients and soil structure and would be another way of composting alongside your bins. You could do this over the whole bed, not just for beans.