SOME fish nibble on plants yes, but the greater majority of fish won't do that (check out my aquariums to the left, I even had plants in the Yellow Lab tank).
And no need for special soil, gravel or sand (which ever you pref) will do just fine. And Pers I'd not mix live & plastic plants, I like things natural lol
The plants, when you buy them, you need to remove these lil plastic pots/ baskets AND the foam around the roots and then plant them in your gravel, otherwise you're doomed to get root rot and kill the plants, not good.
Buy a liquid test kit, anything else is not only inaccurate meaning it'll really only then show NO's & Ammonia when its too late. But also the liquid test kit lasts much longer and won't need replacement (so pretty much you get more use of it for your $)
No air pump in a planted tank. Plants need CO2, with a air pump you're driving that right out, so do not buy one, safe the bucks and get more plants
You wanna have a light over your tank that fulfills 2 things: ~1 watt per gallon and the light should be something called Daylight (rated at around 6500K) that's ideal to grow most plants.
I honestly have no idea about a webpage for UK plants shipment - Had you googeled it?
Plants that're nice & easy and grow fast are: Hygrophilia, Pennywort, Ludwigia, Vallisneria, Rotala.....If you like just cruise through my tanks on the left here and see what plants you may like better then others.
To see the plants I named here's 2 pages (but I don't think neither 1 ships to the UK) Sweet Aquatics AquariumPlants.com Largest online sales / service site for the live aquarium plants & aquarium products community.