New to toys what’s a must have ?
Rabbit vibrator, can be used solo or with partner.
There is no such thing as a must have unfortunately. Different people like different types of stimulation and have different requirements when it comes to things like being waterproof, being quiet, not looking like a sex toy, battery vs rechargeable etc.
Go with what peaks your interest. If you have the budget to buy a few toys which do different things, I would suggest doing that so you can explore what you like.
Generally speaking a good bullet vibrator is a very versatile toy to start off with. It can be used to stimulate lots of different parts of the body, clit, nipples etc and is not as intimidating as an insertible vibrator can be for either you or your partner.
I agree with kelly_michelle. Here are some of my favourite toys, I've also reviewed almost all of them:
Wand https://www.lovehoney.co.uk/product.cfm?p=37246
Cheaper, smaller wand https://www.lovehoney.co.uk/product.cfm?p=37806
Lovely litte double ended dildo, easy to hold https://www.lovehoney.co.uk/product.cfm?p=4667
Glass dildo, great for g-spot stimulation https://www.lovehoney.co.uk/product.cfm?p=36044
Thin g-spot and p-spot vibrator https://www.lovehoney.co.uk/product.cfm?p=36047
Glass butt plug https://www.lovehoney.co.uk/product.cfm?p=32887
Butt plug set of 3 https://www.lovehoney.co.uk/product.cfm?p=40795
Anal beads https://www.lovehoney.co.uk/product.cfm?p=24636
Girthy dildo https://www.lovehoney.co.uk/product.cfm?p=30881
I haven't tried any of these clitoral suction vibrators, but most have very good reviews: https://www.lovehoney.co.uk/sex-toys/vibrators/clitoral-suction-vibrators/
It's also worth investing in a good water based lubricant, a sex toy cleaner, and pouches to store your toys in. =)
I'd go for a bullet vibrator - the Desire, Mantric or Tango ones are very popular and pretty powerful. If your budget is smaller then Tracey Cox and Rocks Off do good battery operated ones.
Add to that a glass dildo (you can use both at the same time - I find this tends to work better than a lot of Rabbits which can be a bit hit or miss depending on your anatomy). Glass dildos make great back massagers as well as feeling good internally. They are waterproof (for bath / shower) and you can use any kind of lube with them, and put them in the fridge or warm water to try different sensations.
Or you could go for a classic vibrator or a g-spot vibrator - plenty to suit all budgets but Mantric and Desire are always a good bet. Classic vibrators are long and straight, whereas g-spot vibrators tend to be shorter and curved to hit that set of internal nerve endings which goes a long way to making sex feel pleasureable. Either can be used for clitoral stimulation too, or in combo with a bullet.
Any of these toys can be used to stimulate a partner's sensitive areas too, if that appeals. Think nippes. neck, shoulders, inner thigh etc as well as the obvious bits - for yourself too!
Have fun messing around and trying things out!
P.S. I see from your profile that you have volunteered to test a few toys. Good for you. You are more likely to be picked if you make some purchases and review those first - this also gets you 20% off your next purchase 
Although I agree people like different things so there’s no universal must haves, when I started out I went for something basic such as a classic ladyfinger (https://www.lovehoney.co.uk/product.cfm?p=15342) that I used primarily for clitoral but can be inserted as well (I still keep one of these in my bedside drawer as a quick go to). I then got a small dildo so I could experience being filled up whilst using the vibrator on my clit, it was similar to this one (https://www.lovehoney.co.uk/product.cfm?p=22814). And finally I got a small slim butt plug because I was curious, the closest on LoveHoney is this one (https://www.lovehoney.co.uk/product.cfm?p=16053). That was a good 10 years ago and I now have over 70 different toys of different types and sizes, but these did me for a good year or two when I started out...