Similar experience and therefore advice as WaxOn above.
I had eldest dd and 18 year old dtwins pass close together two years ago, eldest ds a couple of years earlier.
If she’s not chosen a specific car you can look at some in her budget on E.g. Autotrader, where you can leave the make/model blank and select e.g., lower insurance bracket and smaller engine size to get an idea . Then run quotes on the theoretical cars on Compare the Market, Money Supermarket and Go Compare. I couldn’t get a lower premium with any specific independent young driver insurer, we most often have the best results using Compare the Market.
You can play around with certain things to see if it might bring down the premium, such as, assuming you have long held a clean licence, putting yourself or DH on as an additional driver, selecting a higher compulsory excess and/or less miles, and definitely selecting telematic (black box) only policies. You can also run quotes with prov and full licences to compare.
First year we were with Insure the Box and Carrot (Aviva), the Insure the Box policy was converted from prov to full cover for a smallish additional payment. This year Hastings and Admiral (black box Policies) have been lowest.
We live in Suffolk which lowers our premiums, but mine paid in the first year £700-£800 for 1.4l engine cars worth about 1k. A couple of years in they are paying £500 ish, though two are planning to upgrade shortly.