What's the best child-friendly surface?

[LaTristesse]

So I'm planning on losing a bit of lawn to make a dining area. It's a level area near the house bordered by a path. There's a drainage cover right in the middle of it so I can't deck over it.
Those of you with chidren, what's the best toddler friendly surface to put down? It has to be reasonably cheap too as I don't have much £ to spend. Gravel? Wood chips? Other ideas? Thanks!

You can deck over it as long as you make a access panel to retain access. We have a decked area with a lift up bit for the washing line. we have a small inspection bit bit we just made sure it just had small lengths over it so it could be removed easily.

Decking is good as it flat so you can put paddling pool on it, we put it on some foam mats fist you can also put a sand pit on it.

Anything like gravel is going to be a pain by the drain cover

Ive just barked one side of my garden where the trampoline is. I done it myself using landscapeing fabric and playbark, it was really easy. It looks fine im just hopeing it dries out a bit. I didnt want to get stones as my mam has them and when my daughter falls it really hurts. £5 for 10sqn fabric and £5 per 56ltr bag of bark in b&q.

Fifi... I take it there's no chance of getting splinters off the bark?