I tend to use my own compost on the garden, and anything I can get free from local farms. I sometimes buy Westland peat free compost to use for things like seed growing and potting where I really don't want weeds. It is peat free, reasonably priced and usually available at Wickes or B&Q and I can easily get a couple of bags in the boot of my car, guess you may be looking for more quantity though.
Something to consider, I am gradually raising my beds by putting wood (And a few other things like leaves) under them. Have a look at Meadowlark's thread on Hügelkultur.
Welcome to the forum, have a good explore, there is quite a bit to learn from if you are 'Quite new to this game', see you around.