Hello Fellow Carole!
You spell your name with an E - you must be posher than me
I have an (undeserved) reputation for spending every spare minute on this site, though I admit you will see my name cropping up from time to time.
To answer your last question first, my whole family had a wonderful time!
Re the little biting beasties, I would say the sandflies are worse than the mossies. I felt the ambands did work against flying things, but would only work on the sandflies if you wear them on your ankles, which I couldn't do as my legs were swollen.
My advice would be to start taking anti hystamines before and during your visit, something I left a little late. I don't think anything I tried stopped the sandflies. The trouble is you put repellant on, go in the sea, it washes off and then you have to try and re apply it on damp, sandy skin.
The veterans here can give you loads of advice, as can the locals. The beasts tend to bite more in the wet season (when we went),the evenings and after rain. I was assured by one of the locals ( who were all most interested, and sympathetic, towards my legs) that I would be OK when the sun was out, which seems to have been true.
I would recommend Zanza click to stop the itch as soon as you find a bite, and some cream at night to stop the itch so you don't scratch in your sleep, which is a real problem. I used Anthisan and Tiger Balm. I think Anthisan is better. The worst thing for me was that I came out in blisters. Several of the locals told me to burst them, which I was worried about doing at first because I was afraid of infection, but in the end I did, and was glad I did. If you get blisters, burst them immediately before they get too big. One of mine had a one and half inch diameter and stood proud of my foot by about the same amount! Take some Melolin dressing with you just in case.
My goodness how I go on
Anyway, the main thing is, it didn't stop me doing anything, not even a walk in the rainforest, and a dip in the Caribbean is very soothing for sore blisters.
Enjoy yourself. I want to go back.NOW!
Cheers
Carol

PS. Didn't try Marmite