Welcome to the forum Andrea,
You need about 80kg (4 x 20 kg bags) of powdered adhesive. You get around 4 square metres per 20kg bag and your floor is just under 16 square metres. Go for an adhesive that's suitable for porcelain tiles because, like porcelain, your vinyl tiles are not porous so you need an adhesive that can cope with that. (I'm assuming your vinyl tiles are well stuck down here.)
A 20 kg bag of adhesive should cost about a tenner from a decent builders merchant (you don't need anything fancy from a tile shop for what you're doing).
Grout amount will vary depending on the size of your tiles and the grout gap you leave - but I'd expect for a regular 13" X 13" tile with a 5mm grout gap you would need about 12-14kg. I always recommend grey grout because it looks good and doesn't show dirt.
Have a read of the tiling sticky in the tiling section.
Many thanks for your advice. B & Q were trying to sell me some ready mixed adhesive and grout for 130.00. So I'm glad I came here first before purchasing!
I will shop round tomorrow for the stuff and have a read tonight on the forum and site for tips.
Great place here, thanks again for all your help xxx
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