Hi LTP, welcome to the madhouse!!!! lol. We are not all experts, but you'll find that all of us will try to help if we can.
Comfrey is best in one patch if you can, but it can be invasive, hence hard to get into one place if yours is all over! You'll dig it all up, then those little tiy bits of root you missed will all come up again, and again, and again!!!!lol.
But comfrey is a brilliant fertilizer, especially liquid. I just cut it down when the flowers fade, and put it into a big tub (at the moment, here I only have a bucket, but I have just got hold of an old water tank from a friend's attic, so I'm going to use that. Stick the comfrey in, fill with water, and after a few weeks, you get a foul smell, but lovely liquid fertilier which I think should be diluted about 1:20.
OR, you can chuck it on your compost heap as a good activator, or put in directly on your plot, or use it to line trenches when you are planting things like potatoes.
John has a brilliant article on comfrey here:
http://www.allotment-garden.org/vegetables_and_herbs/Comfrey_The_Wonder_Plant.phpAs to getting rid of all those weeds!!!! Well, we all know about them! Just do it a bit at a time, there are lots of ways to do it. One year OH and I just rotavated the whole lot of my plot (its my garen though, not an allotment!) but of course, tht chopped up all the roots of the docks and nettles etc, then the next year we did it bit by bit, and by the end of it, the weeds that we'd just left were HUGE!! So this year, I covered everything in black plastic and moved a bit back adn dug that bit, then moved another bit back and dug that bit, till it was all dug. A bit was rotavated, but only after we'd got all the perennial weeds out first.
also, most of my potatoes this year I grew under plastic, making little crosses in the plastic and planting my potatoes through that into the ground. Worked well with keeping the weeds off, but something under there kept eating my spuds!!!!!! so next year I'll maybe plant normally, but make sure I mulch better!
Good luck, and don't be despondent, we all get that sometimes!!!!