Sand lizard ?

My greenhouse has alpine grit at either side and an old stone glazed sink under benching. Yesterday evening I found a sand lizard in the sink under a aubergine plant which I had stood in and sprayed with soapy water to get rid of aphids.

With the hot weather I left it in the sink and added some largish stones so it could get out if it wanted.
Thing is ,am I doing right or should I move it into the garden somewhere.
If so where should I put it to be safe.