Welcome to NGA,
@alanh888.
I've grown and propagated FLF for over 25 yr. I grow many 100's of tropicals and because I have so many plants, I make all my potting soils. I'm not sure what sort of nursery or big-box stores you have in England, and thus, don't know what you have access to. Here's a formulae for a simple potting mix, one that is organic yet well-draining:
1. 2 parts composed cow manure (something like Black Kow)
2. 1 part cypress mulch (cypress holds up longer)
3. 1 part coarse or super coarse perlite
4. A handful of 4-6 mo., slow release fertilizer, balanced formulae (I use Osmacote and Dynamite) per 5 gal. of mix
I've found that something like the above media will retain some moisture, will never get soggy, and drains well. In my experience, FLF do their best when you keep the potting soil slightly moist, which is true for most tropical plants.
Good luck and stay safe!