backs going to take hard work im afraid if its rubbly, short of ripping it all up covering with black plastic to prevent weeds, but to be honest, i'd just clear it all. are those trees yours in the back ? any nice bits of rubble you could use a feature and plant ground spreading herbs like thyme or camomile. Rosemary or even some heathers, polyanthus would look pretty here too you can get them cheap on the market , could have a line of lavender, sorry im a veggie and herb person, shrubs im not to good with im afraid i have a thread on here asking to help name mine , just looking at the slope, what is it like on the other side?, the last thing you want is to dig it all up and to have the trees fall over.
as for the front i think it's loverly, i bet you hear the birds chirping away happily dawn and dusk, again a tidy up and a clip back after the daffs have died back *i know they look untidy when they do this i find it annoying* you can pull up and either move, store, give away the ones you dont want and plant ground spreading plants to save on weeding,
what do you want in the front all year round flowers, shrubs, or just a mix of everything?
Weed from one end clear out what you dont want recycle or move rocks, keep plants you want, give away or even swap what you dont want, bark chippings or gravel(smashed up rubble if your having a bad day ) inbetween are resonable weed preventors while you wait for any spreading plants to establish, black plastic is ok but slugs love it underneath and the birds cant get to them,
im afraid whatever you do it will be hard work, but its always rewarding, do little at a time start at one end and move along so you can see your progress instead of trying to do it all at once