I have written about cordials and Elderflower Fizz in the past - just click on the headings in the side-bar to the right here, where you will find step by step instructions and lots of photographs.
If you look at the blossoms in the picture at the top of this page each one of the little flowerettes that make up the whole head, can be 'combed' very gently from the end of the stem. Add the flowers to gooseberry jam once setting point is reached - stir them in very gently. You can replace some of the sugar from the recipe with elderflower cordial to bolster the flavour.
You could add them at the end to Elderflower & Gooseberry Jelly, again, stir through very gently so not to break them up.
If you have an abundance of flowerheads then steep some in a jar with either rice vinegar or white wine vinegar. Make sure the flower heads are covered with the vinegar at all times. Leave for two weeks or so, then strain through kitchen paper, muslin or a coffee filter. Bottle and use in Summer vinaigrettes, for pickles or as a drink mixed with honey and warm water to soothe Summer colds.
Don't be caught out in case you get handed some unexpected ingredients!
Keep an eye on the fresh herbs - they are growing apace now and will be at their best picked young - warm from the sun and dry. Lots and lots of things to make with them - vinegars, jellies, try herb salts - such as mint. Maybe a fresh herb wreath. Masses of variety.
send me some pictures of what you are making.