Dear June,
Sorry girlfriend, there's no "quick fix" for pelvic floor muscles. However, you do have a mouth, hands and a butty hole and all three are capable of a good tight "squeeze and hold" at your command. As women, we always panic about first-time sex with a new (or old) partner. We've gained weight, gravity has lowered our titties, stretch marks, moles, brown spots, etc., and you know what? The guys could care less. All they see is a willing, open welcoming moist vagina that is available to them. Just make sure to use a good lubricant and unless you know his history, have him wear a condom that you provide. Years ago I had a similar situation, instead of fucking, we ended up doing manual and oralsex.
However, there is another easy fix. Get my book "Orgasms for Two" (a very small investment) for some great ideas and ways to enjoy partnersex other than penis/vagina sex. Then tell me all about your adventure. For a more permanent fix, get my Vaginal Barbell and read the instructions. A good investment for your long term vaginal health.
Betty