Gravel planting on high water table

HELP  I live in North Wales near the river Dee and my garden is on a high water table, I have struggled for the past four years since moving here to have a decent lawn, last year I got it looking reasonably  decent with a lot of work and lots of new turfed areas, I went to Australia in November for 3 months and returned in February to find that the lawn was a mess again because of all the rain, the new turf was just mud and the rest of the lawn was moss, so I have finally given up and gravelled it. I want to plant into the gravel, Hosta, Astilbis, Cordyline and Hebe's, can I put the Hostas and Astilbis into the gravel and should I put the Cordelines and Hebe's in large plastic pots into the gravel with grit and gravel below them for drainage