Painting/rendering cinder block wall

Heya, bought a new build house with small square garden, coming up to a year now. Not my dream home, hope to only be here a few years (5-10 max), so not wishing to invest very much in it. That said, there's an ugly concrete block wall to rear that is driving me mad. Going to plant some creepers in the coming weeks but it'll take them a good while to substantially cover it.

In the meantime, I'm considering painting the wall as a stop-gap measure, or maybe rendering it. I'm told I should not paint the wall as then it's very hard to render it (thinking of when it comes to sell the house later). And obviously rendering looks a lot better (except for the fact I'm between two neighbours who probably won't render theirs so either option is going to be dragged down by that). Money is a bit scarce, though, and rendering is going to be way more expensive.

I've two questions then: First is it really a complete crime to paint a cinder block wall? And second, can anyone suggest a rough figure for getting a 6.9 x 3m wall rendered (21m2)? I've very little idea of the kind of numbers we're talking about.

Really appreciate any advice (for a novice), thanks.

Our garden back wall was like that in our last house, with two rendered walls down each side. I painted it and it looked a thousand times better. It probably would have looked even better to have it rendered first, but it's so common to see blocks painted it looks absolutely fine. One note is that you really want to get the paint into the crevices to get a clean look, so load the brush up well!

Plastering is one of the cheaper trades, if you had somebody onsite you'd get it done for €2-300 I'd say. The problem is everybody is so busy it will be difficult to get somebody to do a small job like that and they have to get to site so you'd probably end up closer to €500. I would stick it up on tradesmen.ie, you might find somebody in the area doing a job who would drop in and do it.

There's a price mentioned in a thread from last year here, but as above, expect to pay more per sqm for a small job.

An alternative would be to attach a trellis to the wall and hang plant pots on that until the creeper is established, or attach willow screen.

A builder working on our house a few years back complained strongly about people having creeper on walls. He maintained that the plant sucks any moisture out of the wall and that weakens it.

Saw this on Google:

Are creepers bad for walls?

Self-clinging climbers such as Boston ivy and Virginia creeper (Parthenocissus sp.) do not usually cause damage to wall surfaces, but common or English ivy (Hedera helix sp.) supports itself by aerial roots and where these penetrate cracks or joints they may cause structural damage. Sound masonry is unaffected.

Leo's idea of the willow screen sounds good.

Hello folks, a belated thank you for your very helpful responses. Quotes through tradesman.ie (brilliant tip, thanks Zenith) and a plasterer down the road were 650-1300 euros (talk about a margin of error!), so I decided it's not worth going ahead with it, even the painting because it'll probably look strange with the neighbours' walls still blank. Hopefully the creepers will take care of it quickly.
I did a fair bit of research into the ivy problem and it seems it's definitely an issue for old walls (particularly important for house walls) and not for a new wall like my own. Also it seems that the fact the plant keeps walls dry is actually a good thing! I like Ivy but am not massively wild about it so I'd prefer not to include it. But keeping evergreen coverage of the wall is a priority.
Thanks again ever so much for the time taken to respond to me.