What 'soil' should I put in an old bed?

[Watellz]

Recently moved house and want start gardening.

There's a bed at the rear of the garden, by a fence, hhh facing and about 12ft x 2ft. It's shady and there's ivy growing up the fence but nothing else. In some parts there's the remnants of black plastic sheeting, presumably to prevent weeds.

My thoughts are to remove the black sheeting and some of the soil and replace it with better soil and then fill with Garden on a Roll plants.

Does this sound a good idea? How much of the soil do I need to remove and what sort should I replace it with? All guidance appreciated.

remove ... some of the soil and replace it with better soil
That sounds easy. But it isn't.
Once you start trying to move soil around you realise what a big undertaking it is! Don't bother with the 'removing' part; just do the 'adding to' part.
Ideally, you should be adding to the health of the soil as a continual process so it would be great - as a long term plan - if you could start a compost heap going.

Different plants require different compost (raging from acid to alkaline. Although worm castings and rotted manure are good all round additions. Just add the appropriate compost by backfilling the holes with it at the time of planting.

Now going to Google garden on a roll...

Just keep digging in rotted muck, leaf mould etc. Pull out any old roots. Is it poly sheeting? That's sometimes used if there's something undesirable that needs smothering and killing off. Dig out the plastic and dig it over, then leave it and see what comes up, before you spend a lot of money.

Forget about removing the existing soil - how will you dispose of it? - just add new on top (as you garden the soil level goes anyway.
when I had my garden landscaped I bought top soil by the tonne bag delivered from BPS - they crane the bags into your garden. They also deliver compost.

Garden on a roll is great for ideas but I’d buy plants from a nursery where you can see the quality

I agree with this - I’d leave the bed for a full year before investing to see what’s in there