I've never seen Melcourt compost in our GCs - but you can get it online at various places. Need the room for a truck to offload it though. I'd like to try it and see if it's worth having.
I've been using Miracle Gro peat free. So far so good. Grown everything in it this year, bedding, toms, cucumbers, veg in the veg trug etc. Been quite impressed. Not as 'woody' as others i have been. B&Q's own (Verve) is pretty awful so i would avoid.
@wild edges have you used it for seeds, I find they germinate best in a peat based compost?.